Virtual PC virtualizes your hard disk into a single file. The maximum file size on FAT32 is 4GB, the maximum disk size in virtual PC is far larger. When you store your virtual PC on a machine with a FAT32 drive (as a surprise my tablet came with a FAT32 formated disk) virtual PC will split the virtual hard disk in several files. Leading in very worying error messages when you copy (part of) a virtual hard-disk. JoeN has a very nice post on this. Time for some hard core disk maintenance...
Peter