do you allow to work chkdsk to work?
if the file system is fat32 it's better to check it every you have more time.
if you use win xp or 2000 it's better to convert your drive to ntfs.
it's better than fat32. and have more speed.
the reasons of ruining chkdsk every time are :
1.you take shock some times to your pc ( moving pc or its table )
2.the way of turnoff is wrong. use the shutdown (or restart for restarting) in win to down your pc safety.
3.repeated restart from button on the case make damege for drives.
if you have to do it, recomended to hold down the button of power of pc (in front of the case) for 3~5second .
4.some reason i don't know.
goodlock