trying to disconnect a usb drive and it won't do it

[sparks]

I am using windows xp with sp3.
I have a 750G ext hd and moved over some big files, up to 6 gig.
I have the drive set to NOT cache files and quick disconnect.
If I move over files and just unplug the unit the last file copied is corrupt.
So I deleted the files and tried again. All the files are copied over, took almost an hour.
I then tried the tray icon to stop the drive.
I get The device can not be stopped right now try again later.
This is for the last 2 hrs after moving over the files.

What is up and how in the world can I move over the files without corruption?

 

[alphanumeric]

I get the same message for my USB hard drive but not for thumb drives. I just wait a couple of minutes after its done (drive activity stops) before I unplug it. Haven't had any problems with corrupted files.