I have had a similar problem with my machine with the last 3 motherboards I have had in it. I notice that when running moderately overclocked that after running for 4 or 5 days this will happen. It is usually triggered by my double clicking on a folder or trying to open my computer or a folder. What happens is everything except the desktop picture will dissappear, explorer will quit, and then reappear and I can then continue as normal. I am not 100% sure this is caused by the overclocking, I am just assuming it is. Has anyone else had anything like this on a machine? If it is caused by overclocking it seems to be the fault of the FSB setting because it will do it with the CPU running at stock speed but the FSB speed cranked up somewhat.