My XP system, which has been working fine for months, can no longer read any fat formatted media. This includes floppies & memory sticks.

On mixed partition hard drives it can only use the NTFS partitions. DVDs, and CDs are ok.

Any attempt to read fat12 or fat32 formatted media brings up the “drive not formatted. Do you want to format it now?” message.

Now get this. It will try to format a fat32 drive but, after a while, pops up the "unable to complete" message (this also happens with floppies). But, if you pull the drive and stick it in another machine, the fat32 partition is there and working fine. In other words, it can format a fat32 drive but can't read the formatting it just did!

Now tell me you have heard of this one before.

All hardware is working perfectly. The problem only appears under XP.

Virus scans see nothing. I suspect Registry corruption.