The build is about a year and a half old, but in the last three months I've had it blue screen and then refuse to boot three times.
Each time the error I got was "verification of knownDLL failed". I was able to fix the problem by reimaging the hard drive, but obviously this is not a long term solution. The first two times I got the error and had to reimage I was running Prime95 to test my overclock, but the third time I was just uninstalling an ATI driver that was acting up.
I've run memtest and my RAM seems to be fine. I think the problem might be the HD, but I'm not exactly sure how to test it.
I'm on Windows 7 Enterprise 64-bit with a i7-920, ATI 4850 (Crossfire), and a 1TB WD Black.