login as root at the console prompt type do-vesa then type startx
That got the vesa display working again. Unfortunately it is now offset too high by about 300 pixels.
I have found that by setting the color resolution to 24bpp improves this, so it is now only offset by about 50 pixels.
The boot splash screen displays perfectly. The display problem seems to be only once X kicks in.
I've played around with almost every resolution but the best result so far is with its native 1366x768.
Also booting with the original PCLINUXOS 2010.12 kernel doesn't seem to make any difference.
The original install was working fine at 1024x768 but I never tested the native resolution before updating everything. However I'd guess the native 1366x768 would have worked as well.
All I need to do now figure out how to move the screen display down a little and I'll be good to go...