This is very interesting. I hope DigiSupport reads this veery soon.
Osx 10.5.6 is just so full ofbugs. So unlike apple.
I just had a look at the .6 update page:
http://support.apple.com/kb/HT3194
Includes this:
Graphics
* Includes general improvements to gaming performance.
* Includes graphics improvements for iChat, Cover Flow, Aperture, and iTunes.
* Includes fixes for possible graphics distortion issues with certain ATI graphics cards.