Interface display blur error on screen when scrolling
It looks like a screen driver error, or incorrect use of a graphics card process by the application. (pure conjecture)
I've found two references to this problem in Apple discussions - no answer or solution was provided to either. Apologies if I haven't found any reference that might have solved it.
It's a shame I can't post a screenshot.
Dual 2.3 GHz PowerPc G5 Mac OS X (10.4.8) 2.5GB DDR SDRAM