It's just one of many bugs with lots of ram and various versions of Windows. You didn't supply any detail so here's just one of the dozen or so articles about this -> http://support.microsoft.com/kb/929734
Remember I have no details to work with. But it is a known problem with many versions of Windows.
I have an issue with my motherboard. If I install any new RAM other than what I used when I built my computer I can't use sleep mode. The reason why, is that when I try waking my computer up, my processor idles at 50% and windows becomes EXTREMELY unstable and I have to shut down. I have none of these issues when I boot up and my computer passes all stability tests. So there is something wrong with the motherboard somewhere. So my question is, should I install the new RAM and never use sleep mode, or keep my current RAM and be able to use sleep mode? And I don't want to rma the motherboard because if I am going to go through that hassle I will just buy a new, better motherboard.