You may recognize the situation. You walk into a store to purchase some merchandise. The cashier waves her wand across the bar code. The price pops up on the screen -- only it's the wrong price.

It's a common occurrence -- at least for those of us who pay attention. Sometimes it's our fault. We may have read the price wrong at the shelf, looked at the wrong label or confused the size we're buying for the one that's on sale.

But not always. Sometimes the store is to blame. Maybe a sale just started (or just ended), and the price shown on the shelf is different than the price in the database. Whether it's a mistake or not, it always seems as if the cashier has the higher price -- and that it was done on purpose.

So when we get to the cashier, we're surprised. If we're confident, we mention the discrepancy to the cashier, maybe even make a fuss. If we're shy, we grin and bear it, perhaps even vowing never to return to the store that "gypped" us.

In some cases, the manager can override the price in the register. But if he won't, do we kick and scream and hold our breath until our faces turn blue?

The other day I ran into a variation on this problem. My wife asked me to return several items to Sam's Club. Like a good husband, I threw the items into the car, drove down to Sam's Club and approached the customer service representative. She gracefully asked for my receipt, waved her bar code scanner over it to look up my original transaction, and then scanned the bar codes on the individual items.

Strangely, not all the items that popped up on the screen matched exactly the items on my receipt. She offered to refund my money for the matching items, but could do no more than give me a gift card as credit for the nonmatching items. After unsuccessfully pointing out that the items match the price and that only the descriptions are different, I gave up and accepted the gift card -- even though I knew I should get cash.

The customer service rep couldn't comprehend that the items were wrong because, in her mind, computers don't make mistakes. I couldn't convince her that people make mistakes when entering information into computers. The item kept coming up on screen with the same price, and a description that didn't match the one on the original receipt. I think somebody simply corrected it since the time of purchase.

As so-called big-box retailers grow, so will these computerization mistakes, because big-box stores tend to rely on automated systems. Their procedures generally are less forgiving then the mom-and-pop store; and they often make it next to impossible for the local personnel to do anything out of the ordinary. For a recent large transaction I made at CompUSA, it took almost three months to correct.

The stakes are high. Let's say that only twice a day somebody walks into a big-box retailer to return a $20 item, but is forced to accept a store credit. Over the course of a year, that retailer gets to hold $14,400 in customer money by giving credit instead of cash refunds.

There are thousands of these stores, so the impact could be tens of millions of dollars annually. All because chain-wide computerized point-of-sale checkout systems are unforgiving. Astute personnel can fix the problems. Yet they don't always have that power -- making customers the losers.