It was not a consistent error type,I was cycling through several. I no longer have my paper scraps with all of the errors and notes written down so I can not say how many times this came up exactly ( went looking online for all the errors that I had-sparse information) .
No other games caused the problem, just UT3. There were several workarounds I found on the web that supposedly would stop the GAME from crashing, but the Editor Always crashed it during a light rebuild.
I see I missed the fact that you run Vista, so there may be other things involved. It is about a five minute test with the memory change if you have 2 sticks (and not 1) and since you have no problems altering your system (pwr supply,video card) at least you should be able to verify the memory this way and not have to think about it later . If yours is the post where the old, good system was given to a friend and your copy of UT3 worked on that then what are the differences between the systems that could cause a good copy (it worked before) of ut3 to have problems on the new system, bios/Motherboard Drivers/vista? Perhaps you could ask for anyone having your type of hardware setup to post if they have the same thing and how they might have fixed it...could be a short cut.