Hi,
Have the same problem, psychedelic colors in triangles and other shapes etc. getting worse when you try to keep going. Happens at random seemingly. This is same on our two iMacs 2GHz Intel Core 2 Duo 1.5Gb Ram, both running VWA + RW 12.5.3. One iMac runs Tiger the other one Leopard.
I have target disk installed the first Mac from a G4 iMac, then from that Mac onto the next one then upgraded one to Leopard.
Have not found a solution.
This may help: Quick fix each time it happens: Sleep and wake computer.
