I was having this problem but only after it was rendering for a while and hit a certain area. I was using Image maps and even optimized them to no avail. I'm running a P4 with Hyper Threading which was enabled when I got this Error. Might have been just dumb luck but what I did was reboot, go into Bios Setup, Disabled Hyper Threading and all was fine.

Of course TG sucks all the Pipeline up now and makes it tough to do anything else while rendering. Just a thought in the chance that you have an old P4 with HT?? I know, someone is going to say, even with HT enabled and Task Manager saying TG is using 50% that TG is really using 100% and not 50% like Task Manager says.

? All I know is that since I disable Hyper Threading, I've had no problems rendering.
Good luck just the same.
Jay