Sorry I cant help you there. I have the same problem and I have been looking on UT3 forums every where but the things people say to fix the problem doesnt help me at all. I installed patch 1,2,3,4,5 when they came out but none of them fix this problem. My windows version is XP Professional. Sorry I didnt spell that right Im in a hurry. So this realy sucks. My new computer broke so im stuck with this old one and UT3 was working perfectley on that computer. VERY ANNOYING!
not sure if its been posted here yet, because 29 pages is a lot of reading but razor, did you try deleting the published, unplished and src folders in my documents then try running the editor? thats what fixed my problem