Why do renders, and renders only, crash so much to the blue screen of death? In fact, when it's a render that takes more than 10 minutes long, it crashes at least 60% of the time.
When I was using 8.1c with a 64 bit OS (Vista in my case), I had to create a huge page file (12GB) to work around this issue of render crashes. It worked but you may have to also tweak the internel preferences in Vegas to free up more RAM still.
Worth trying.
Vegas 9d is working fine on my current system (as far as stability, jpeg handling, etc - a lot of the common issues were resolved.)
There's no V8.1c, it's either 8.0c (32 bit) or 8.1 (64). 8.1 is a piece of junk, a beta they released as final. 8.0c has that hack that works for most people.