That pretty much falls outside of RO, but I can try to help with my meager knowledge. Can you tell me the stats of your computer?
Right-click on 'My Computer' and select properties, you should have a bunch of information right there.
Also, make sure your disk is not full or near full (click on My Computer to enter it, then right click on your main disk (usually C
go into properties, do you have a lot of disk space available?
Have you done a defrag lately?