hpurey:Or just shutdown your computer, then turn it back on.
I never shut my Computer all the way down ever. Rule of thumb for me is .....Always restart the computer before playing any video game even if it is just a Flash game. This free's up all system resource because even though you shut processes down Windows has a funny way of running slower than usual after being on for a while even if it is not being used. I used to reformat my computer every 3 months when I was a hardcore gamer to make sure that I have a clean OS running without all the garbage that is collected by windows after the initial install. You know a computer runs amazingly fast when you first get it and reformatting makes it that way every time.
Windows (microsoft) have definitely improved over the years without having to reformat at all anymore but boy I remember Windows 98 OS and that was a piece of crap OS especially for gaming purposes. Windows ME was a better OS at the time but needed reformatting often.
Remeber to do a clean back up or mirror image before doing anything to your OS or your asking for trouble. Make sure you have the original reformat CD if one came with your computer or just make one using the system tools provided by Microsoft from your Control Panel. If you have no idea what I am talking about then just forget about it and do nothing.