@ sushi_joe - oddly enough i experienced the same problem. Windows would stall at loading/welcome screen or when at BIOS - this was usually about a very long freeze and ofcourse the occasional, freezes when everything was loading at the desktop level.
I located the culprit for all these problem's. Turned out to be a delux mouse that i used as a replacement was causing the hangover
(don't mind the pun) try using another set of keyboard and mouse. And see if the problem persists. If it booted the first time, then maybe its with incompatible hardware. Go over the manual, check if rams are in their right slots(usually people mistake in interpreting the colors on the slots.
BTW, can we have your entire system specs, please ? we can move on from there.