Compaq has issued a customer advisory notice for the SD memory card. This may fail "after a short period of use". in the iPAQ H3800 Series Pocket PC, the company says.
The problem appears to be confined to a few batches of 64MB and 120MB cards, and you can check if yours is one of those affected by looking at the LOT code at the back of the card. If it's a dud, you can get a replacement, although that may not help you recover any data that you have lost.
There's more on this at Compaq's web site.
The advisory is buried away in the site, unlike the recent fiery notebook adaptor recall, and interestingly enough, it carries a February dateline. Our contact who thoughtfully supplied us with the link above (you kinda have to know where it is to find it) insists that it made its debut on the Compaq web site on March 22. Now that can't be right, can it?