HP and Microsoft generated lots of positive buzz last week with their Black Friday promise of 40 percent refunds on everything in the computer giant's online store. The promotion translated into huge discounts on HP desktops, notebooks and other products.

At least, that was the idea -- before consumers were hit by a double-whammy of glitches.

First, Microsoft's Live Search Cashback site was down for a good part of the day, preventing many online shoppers from taking advantage of the Black Friday cashback promotions from HP and others. Now, some of the people who did get through to the site are reporting that they received a mere 3 percent cashback from their HP purchases, not the promised 40 percent.

The problems have frustrated many of the people who were most looking forward to the promotion. Xavier Lanier of Notebooks.com, who had blogged enthusiastically about the "ridiculously good" HP cashback deal last week, is now working on behalf of his disappointed readers to figure out what happened. His inquiry to HP put the blame on Microsoft for the Live Search Cashback downtime.

The cause of the much-smaller-than-expected cashback discount isn't yet known, but it appears that many people have been affected. People posting on TechCrunch, Twitter, Notebooks.com and Fat Wallet are reporting the same problem. It's not clear if the glitch affected only Live Search Cashback discounts through the HP store, or cashback promises from other online retailers were affected, as well.

I've asked a Microsoft representative for more information on the situation, and I'll update this post depending on the response. Please leave a comment below if you've experienced any of these kinds of problems with the Live Search Cashback promotions.

Update, Monday morning: Microsoft unveils 'instant' cashback; working on fix for Black Friday mess.

Update, Monday afternoon: Microsoft promises full 40% refund to HP customers hit by Cashback glitch.

Update, Tuesday evening: Microsoft vague on prospects for reviving HP's Live Cashback deal.