I do not think this problem has anything to do with Windows XP. I have this problem with only one of three Memory Sticks. The stick can't be read by a card reader on Win2k or WinXP, the DSC-F707, or the DSC-F717 (which is the camera I used). The 128MB stick worked fine as I filled it to capacity. It then lived in a thin, single-stick case for a week in a backpack, an 8 hour flight, and a snowcat ride in the same backpack. It was after all this that I tried the stick again and it didn't work. One interesting thing is that first I filled a 64MB stick with 39 files then I filled the 128MB stick. The card reader shows me that 64MB of the damaged 128MB stick is used by 39 files. The F717 camera shows me that the damaged stick has 39 files on it. Only I can't view them and get a "File Error" with a blue screen where the picture should be. After scrolling 3 times I get the "Format Error C:13:01" message. So the 128MB stick thinks it is the 64MB stick. I wonder how that happened. The stick worked for 128MB pictures worth. So I think it was damaged in transport. Recommendation = get a rugged case for storage. BUT, why does this 128MB stick think it is the 64MB stick. Did the camera mess up? Or was it the memory card reader I first tried to read the card in? (First I read the 64MB and then the 128MB using the reader.)