you didnt change operating systems? my only guess is that u have it set for NTFS and now ur trying to use it on an operating system that only supports FAT32. Did you go 64bit? Did you remove the card 'unsafely'? I know it can corrupt flash drives. honestly i havent even used a sd card with a pc before.
I have not changed anything with my laptop since the last time I used the SD card, which is what frustrates me. I have the 32 bit Windows Vista, but I dont see why that would matter since I have used it on the same laptop before. I dont think its corrupt, but there does seem to be an issue when I try viewing the files.