I recently had the same problem you are having. I hit cntrl+alt+del and first checked the processes. I noticed that there was a process eating up 16mb of memory and had no idea what it was. The process was lcza.exe. I searched for the process on google and nothing. Finally I found a forum that said this was a nasty ad process. Ad aware would not pick this up for the life of me, well finally today I updated adaware and there it was, it brought up the process as being adware related and no more problem, so just make sure you are updating adaware before every use. And check all the processes your computer has running and start a process of elimination. It took about a week for adaware to come up with an update for my problem.
<i> If the creator of the human body is "The Ultimate Engineer", why did he put a recreation site right next to a waste treatment area? </i>