Quickest fix is probably to use an alternative browser such as Opera: click here or Firefox: click here. That obviously introduces a new problem in that you have to learn how to use them, but I for one would never go back to using IE7 as it is now.
Otherwise, you need to diagnose the problem. Not enough information given for anyone to guess what the cause is. Try a general disk cleanup and defragment; delete browser cache, virus scan, etc. Always worth doing regular maintenance tasks like that, and that sometimes resolve problems.