No display after upgrade to 9.04

[Bob Cortez]

I'm at wits end, I've tried everything I can think of and from what
I've research. This is an online upgrade from 8.10 to 9.04.  I
followed the directions at http://www.ubuntu.com/getubuntu/upgrading .
 This is my hardware - Gateway Laptop MT6728 Intel Pentium Dual CPU
t2330 @1.6GHz 2 GB Ram 32bit.

The upgrade appeared to go just fine.  No warnings other than turning
off third party repositories. Booting up goes fine right up to where
the log in screen should be, and all I get is some screen flickers
changing from dark to light then back again.

I'm able to use the live CD fine. I was able to install 9.04 fresh on
a different partition without this problem.  I've tried to reinstall
gdm and ubuntu-desktop and get the same problem.

What am I missing here?

Thanks in advance for your help.

Bob