This lock up happens 100% of the time when I select a screen
saver called 'Halo' under Gnome's desktop settings.
This lock up also happens occasionally when I reposition my
terminal window.
However, when the colour is reduced from 16b to 8b (YUCKS!)
everything works fine.
If I want 16b colour, I have to make do with 87Hz Interlaced
mode for my monitor (YUCKS!).
I have a monitor capable of doing 1600x1200@70Hz NI.
Any suggestions/help??

Thanks.