external drive & trash bin problems

I have 2 Western Digital dives attached to the computer and I am having issues with the drives appearing as read only. IF they appear as write AND read then the computer will crash within maybe 10 minutes, if they appear as read only then it will work for a while, both are pretty new drives (less than a year) and both are FAT formatted. They seem to work fine on my macbookpro, just not the Imac, although they are both on the same OS.

Also, possible related, is the fact that when the drives appear as write and read then if I try to empty my trash can there is apparently 25,000 plus items in there. This also disapears when the drives are read only. I'm thinking maybe it's stuff from the drives I'm trying to delete that are causing the problems with the trash as well?!?

I have 2 accounts on this computer, however I am logged in as admin, and it does the same in the common account as well.

I managed to force delete everything in the trash one day, but that only made the external drives act up and the computer start crashing more, this is why I think they are both connected. I think there was something I tried to delete from the hard drive that it didn't like. It also crashes if I try to empty the trash when it has the 25,000 items in it.

Any ideas?