Binary package hint: xserver-xorg
When I first installed Lucid on my T500 I believe everything seemd to be fine with the display. Recently though the screen has started giving flashes -- as though there was some form of sync problem for the display. The flashes are of irregular frequency and occurrence. I haven't yet seen any pattern to the behaviour. They are however exceptionally annoying.
I believe I am using the Intel chipset graphics device -- I am not actually aware of how to switch to using the alternate graphics hardware, but I am told it is not worth bothering with, so I haven't.
I am using the Compiz window manager so I guess the problem could be there rather than with Xorg.
There is no xorg.conf file so there is no overide of the default behaviour.
I am not sure what programs to run to give useful output for this problem. I have attached the current Xorg log file.