Not sure about your WEI, which is pretty useless anyhow, but the first place to check when games are crashing is heat. Check your temps, especially your GPU and CPU. Memory can also be a culprit. Memtest86+ should find any ram problems.
WEI isn't a good judge of hardware, you can use Hardware monitor (volts and temps), prime95 will stress your CPU, as hawkeye said memtest will see if you have a bad dimm. and i guess heaven or future mark will stress your GPU... just ways to put stress to see what's causing your problems.
Thanks for the input - I'll try running/monitoring some of that tonight and let you know what I see.
I did install a CPU cooler and I'm not OC'ing, so preliminarily, I don't think I have an environmental issue. I think it is possible that something is flaking out (rarely) and If I had to guess, it would be CPU or MEM (or mobo?) - the GPU frames rates, temp and such seem fine - GTX 570 2.5GB btw. And I have played with the Nvidia utils in the past.
You didn't list your CPU and GPU temps while idle and under load. I don't think 3DMark stresses the video card long enough to heat up to it's max temp, unless you can tell it to do so many passes. You might need to record temps while gaming.