[Cube] Misterious Black square around my cursor

[Bumala, Robert W]

I installed the latest OS update to my cube (10.4.8), and I got this
thick black box around my cursor.  I thought that it might be some
accumulated OS corruption, so I did a clean install of OS 10.4, and the
box went away, I then ran the update and it's back again.  I also have a
Mac Powerbook G4, and I ran the update there with no problems at all.

Anybody have any clues what this might be?

Thanks,
Bob.