The anguished cry coming from a neighbor's window late at night doesn't necessarily signal a burglary in progress, a battered spouse or a bloody accident.

These days, it could just as easily be the primal scream of someone who's spent three hours on the phone with tech support, watched helplessly as a hard drive crashed, or failed for the umpteenth time to unsnarl a software glitch that keeps freezing the screen or has stopped the printer cold.

Now more dependent on home computers than many would have dreamed even five years ago, low-tech people dragged into a high-tech world face these frustrations with increasing frequency. Heightening the headaches of an ever more wired world are: increasingly complex software, an epidemic of viruses, a boom in home-networking and pesky programs, known as spy-ware, that insinuate themselves into home computers from certain Internet advertisements.

As unnerving computer or software meltdowns might be, they've created a market for a number of local home computer repair companies that either have gone into business to pursue primarily residential work or seen calls for their on-site services climb sharply.

Sewickley-based Computer House Calls, for example, which started two years ago to cater to residential customers, has since hired three technicians and seen its client list swell to more than 3,000, said Jay Armstrong, who left a consulting job with Management Science Associates to found the company.

Friends and colleagues encouraged him to start his company, predicting that the computer glitches that confound others might just provide the entrepreneurial niche he'd always wanted to find.

Now, "I run a firehouse," he chuckled.

At six-year-old InSync Computers, Inc., in Bethel Park, "I'd say there's been a 50 percent increase just in the past two years in the on-site [residential] business we do," said founder Larry Vittone. He said the business has soared with no advertising but word-of-mouth and is outpacing demand among his small business clientele.

Across the country, the frustrations of the technologically unsophisticated have even spawned franchisors, such as Norfolk, Va.-based Geeks on Call, and caught the eye of at least one large retailer, Best Buy, which acquired the Minneapolis-based Geek Squad a year and a half ago and plans to take the home repair service nationwide.

None of this surprises Sara Kiesler, a professor at Carnegie Mellon University's Institute of Human-Computer Interaction.

Personal computers had found their way into more than 60 percent of the nation's homes, according to the 2002 U.S. Census, but "they're still not appliances" in terms of user friendliness, she said. "The home computer can still be daunting."

"Almost everybody I know has had some painful experience" with a computer at home, said Kiesler, including herself. "It rarely ever becomes a nightmare at work" because most workplaces provide in-house technical support.

Kiesler, of course, simply takes her home computer problems to the tech support gurus who service her CMU office.

But others often don't have that luxury.

Many, Kiesler said, rely on tech-savvy family members or friends, according to her research.

That's what Mary Kirsch, a certified public accountant, first did when she left the company she worked for and became a self-employed business consultant working from her Edgeworth home.

But teenagers "aren't always available when you need them," she said. In addition, while they often have the technical skills to fix a problem, they either can't explain what it was to the client or don't want to be bothered. "It's kind of like a black box. When they leave, you hope it works," she said.

Armstrong at Computer House Calls now does frequent work for Kirsch, often patiently relating the simple fixes that she could perform on her own.

With both household financial information and business files stored on her home computer, Kirsch is all too aware of how entangled she's become in the wired world.

Any glitches, she confesses, can evoke a little "panic." Sometimes there's good reason. Kirsch re-booted her computer one December day after her e-mail failed to respond and found herself staring at what techies sardonically know as the "blue screen of death." The blank monitor often signals a hard drive failure, as it did in Kirsch's case.

The bad news: Because she had no back-up system, all of her files were trapped, perhaps even irretrievably. The only hope of recapturing any of the data was hiring a file "recovery" vendor for about $500, Armstrong of Computer House Calls told her.

Kirsch said the cost was the least of her concerns. She hired the out-of-town vendor Armstrong recommended, shipped off the failed hard drive and waited apprehensively. A few days later, in a tearful phone call, the recovery tech tried to calm her. "Don't cry. We'll take care of this," she recalled him saying.

Kirsch said the vendor was able to recapture about 90 percent of her files. "I was very happy."

Armstrong has since installed a backup system for Kirsch as he did for Claudia Pryor, a Bell Acres customer, who booted up her computer one day only to find "all of my icons floating on top of each other."

"They were making semi-circles on my screen. I didn't have a clue what had happened," said Pryor, 60, who, along with her husband, depends on home computers both for personal and business needs.

The problem Pryor had was a virus.

Indeed, home repair services around the region said widespread virus attacks have driven much of their recent business.

Jeff Tapolci, of the Mt. Lebanon-based Computer Comfort division of PghConnect, said "viruses are the big thing."

Computers also are susceptible to slowdowns and other problems because of a proliferation of so-called spy-ware, the kinds of programs that are downloaded when users click on certain ads. The software downloaded by such ads -- which sometimes are disguised as error messages or options for improving computer performance -- are designed to collect information on a home computer user's Internet habits.

However, they can unleash swarms of pop-up advertising and slow needed computer functions to a crawl.

Tapolci said his firm also still fields house calls for lots of "stupid problems," such as blank screens owing to something as simple as a monitor becoming unplugged or error messages that occur on start-up because a floppy disk has been left in the drive bay.

However minor, simple problems still can stymie the home user, and many confess they're lost without their computers, even with no home-based business needs to serve.

To Zureta Jones, an 80-year old Indiana, Pa., resident whose nickname is Timmi, the home computer "is my lifeline." It enables her to e-mail her four children, three of whom live out of state, and keep track of volunteer projects.

"It's my tie not only to my children and relatives but to my church and social life. I absolutely panic when something malfunctions."

Lately, Jones can't get her printer to print her brokerage statements, though it prints everything else she needs. Go figure.

The young man she's relied on to unravel such problems, Eric Barker, ran his own small business doing house calls as a junior high school student. He's since earned his degree at CMU and become a full-time consultant, though he still does residential work as a sideline.

Barker, who majored in information systems and minored in psychology, isn't surprised that the part-time work he relied on before college is becoming a full-time business for others.

"The computer is very non-intuitive," he said.

Some sophisticated home needs also are making home service more and more of a necessity.

For one thing, telephone support services offered by hardware and software vendors are becoming the butt of jokes. Those who've tried them tell war stories of endless waits and often confusing guidance, all the while running up costs that often are billed by the minute.

There's also the fear of losing files, such as household accounting data, with no one to hold accountable.

Although home repair service isn't cheap -- with local quotes ranging from $45 to $95 an hour -- a growing number of customers seem to prefer hands-on help.

What Pryor likes about Computer House Calls, she said, is "personalized service in a world where service is now push one, push two, push three" and the next available attendant will help.

When a problem arises, "You want to see someone and talk to someone," she said.

Nor are all home computer problems amenable to over-the-phone or even drop-off service.

For one thing, more people are tying multiple computers into home networks and also are tied into broadband Internet connections that might also be a source of problems, said Vittone at InSync.

"We're going into homes that are doing as much [with computers] as a small business," he said. "I've got people with six computers in their homes all wired on one network."

Vittone said one such customer recently retained him to install a home server to store his children's downloaded music and game files.

"There's also more multimedia," including systems that tie together such electronic gear as plasma displays, cable television, stereos and DVDs.

Even installation and maintenance of sophisticated antiviral software, spam blockers, firewalls and the like, can require on-site expertise.

With home networks, routine maintenance needs aren't too different than those routinely provided in office settings with information systems departments to serve them, said Leigh Weber, owner of Philadelphia-based Weber Consulting Services and a board member of the Independent Computer Consultants Association, a St. Louis-based trade group.

As things stand, service calls are typically in response to problems.

"A lot of people aren't diligent, and they don't pay attention until something corrupts their machine," Weber said.

"The residential business model isn't very well established, but I would guess it's going to be more in the vein of the heating, ventilating and air-conditioning guys who come in and check [a homeowner's equipment] once a year."