external hdd problem

hi there!
i wonder if anyone can tell me how i can open jpeg and doc files that are on a freecom classic sl ext hdd.when i try to open them the error message pops up saying cant read file header.would i be correct in assuming that if these files were saved from a laptop running win98 to the ext hdd which is fat32 then they might be unreadable using w2k (ntfs) or xp home?
also the files are in a compress and secure file which seems to have tagged them all as .pms file extensions after the .zip/.jpeg/.doc filenames.
would appreciate any info.
thank you.
caskstrength.