Ubuntu/GNOME Problem after Running GIS-Knoppix LiveCD

I tried the GISKnoppix LiveCD on my up-to-date Ubuntu 5.04 installation. I
downloaded the ISO 27Aug2005 and verified the MD5. I
burned a CD and booted it. It came up fine, and I tried a number of the
applications. I did not save anything (knowingly) to local disk, but I did
access the local disk to verify that it was mounted.

Now when I cold boot Ubuntu, there is a 5 MINUTE (!) delay between typing my
username/password and seeing the GNOME Desktop. In between, the mouse works, but
all I get is a blank tan screen. Once it comes up, everything seems to be in
order. I notice no further delays.

I can log into the machine via SSH over a LAN during the delay period, and the
machine appears to be running just fine.

The LiveCD (which uses KDE) obviously scrogged something. Can anybody give me a
hint how to get my system back to its nice, fast performance?

I'm guessing the LiveCD somehow messed up the HW probe, but what to do next is a
mystery to me.

Thanks in advance for any help.