Hangs when shutting down pc.

I'm embarrased to be doing this.
I just downloaded a fresh copy of NOD32 and I'm having the same problem I had with it a while ago.
When I shut down my pc, I get a rectangular box pop up stating that a drive is open or still in use.
I can't find the thread here from last time, but I remember that the cure is as simple as unchecking something and or in the BIOS.
This problem is serious enough that if left unattended, the pc will not shut down. Which means I can't use NOD.
Hope somebody else can help.
I have a pc w/XP Pro, SP2. There are NO drives being used when I try to shut down. No disks in the drives either.
I know from before, that when I uninstall NOD, the problem goes away.
Thanks,
J.

 

RONJOR,
Thanks. And yes. That's the one.
Thread need not stay open.
J.