What format is the external drive?
General information on I/O error -36 - http://fuzzy.wordpress.com/2006/12/10/ioerror-36/
General information about error -36 - https://discussions.apple.com/message/18221459 - bad disk or format; try using Terminal to delete file.
Error -36 reported when copying files to external drive - http://discussions.apple.com/message.jspa?messageID=8467699
Error -36 and filename characteristics - http://discussions.apple.com/thread.jspa?messageID=9629287 - FAT drives may not like all Mac filenames
AD topic on Error -36 trouble shooting - http://discussions.apple.com/thread.jspa?messageID=8586572
As a general note, although you see only 1 Trash, trash is stored on each drive separately. That's why it appears and disappears as you remove and connect the drive, and when you tried ot move it to a different drive it just copied the files to the trash on the other drive as any normal file copy would.
Thank you Linc. Disn Utility worked on 1 drive. My 500g external. However, not my 1T external. On the 1T I ran the repair utility 3x. On the second run it cleared all but 1 file. After the third run I ran verify disk and it said errors were found but cannot be fixed. I ran repair disk again and the trash is empty!!!
These 2 drives held previous backups from a pc. I'm going to use them to backup my imac now. Should I format them for Mac or is that not necessary? I don't have formatting software for them anymore. They are Seagate go flex and free agent. I know the 1t Free Agent, is a windows NT filesystem.
For optimal Mac use you should format them to Mac extended. If you are not going to use these with a PC then definitely go for Mac formatting as this will help avoid problems such as you just encountered.
Disk Utility should be on your computer and is all you need to do the formatting.
Pondini: Formatting, Partitioning, Verifying, and Repairing Disks... - http://web.me.com/pondini/AppleTips/DU.html