I have not posted back to this thread for some time as I have been monitoring my mini since it's update to 10.4.7. I can confirm that I have not had a repeat of the issue since it's update. Note that if people are experiencing these issues with the 10.4.7 update, that they should re-apply the update that can be downloaded from the following:
The reason for this re-application is that the initial build of the Update missed some OpenGL changes. Subsequently, early updaters will not have the most recent build of 10.4.7 (your build number should have an "a" at the end for the most recent build). To view your build, select "About this Mac" from the menu, and click on the 10.4.7 which will cycle through some items (like serial number, etc). When you see your Build Number, it should have an "a" at the end.
Will post back if there are any issues arising, but I believe this to now be resolved.