I know I mentioned it before and it may be a shot in the dark, but I had a similar problem that was only solved in a very unusual way.

I too suffered frequenly lock ups but only when using Video Factory and was about ready to throw in the towel. More out of desperation than anything else I decided to drop my clock speed down from the rated 1200Mhz to 1166Mhz. And for reasons unknown that did the trick. So if you have a motherboard where you can fiddle with the clock speed in the BIOS (only some allow it) you may give that a shot. Since I did VF is as stable as a MI tank. My guess, I have a very high end motherboard, a very fast processor and super fast DDR memory, maybe things were moving a tad too fast on the bus and that, more than any flaw in VF was the problem since any video editing software will really push your PC to the limit. BTW Craig, if you're reading this, that was some typo I made. I don't have ANUS motherboard, rather a ASUS A7A266. LOL!