I am using 10.6.8 on D630 intel 1440x900 with a dell port replicator and an external monitor. Everything works fine except at random times the UI freezes completely. I had the same problem in Lion as well, on the same machine. I followed the EDP bootpack process to install 10.6.8. There is nothing in the logs but I have observed that this problem happens under certain conditions that I am listing below. Please feel free to add your observations and hopefully someone can pick a pattern and fix it.
- It started happening after I installed Quicktime version 10.0. Recording a screencast in Quicktime is one of the surest way of triggering a UI freeze.
- Editing large movies in iMovie'11 version 9.0 build 1073 can also trigger a freeze but not as often a recording in Quicktime does.
- Viewing a content heavy page in Safari can sometimes trigger a freeze.
Common culprit in all of the above is Quicktime so that might be it but I am not sure.
If it is working well for you then please let me know what version of Quicktime of iMovie you are using.
Thanks