Clear your temporary internet files and cookies by selecting Tools>Internet Options and under History select "Delete...". From there a pop up should appear and click "Delete files..." and "Delete cookies...".
If that doesn't help, you might have spyware. Believe it or not, most computer that have spyware don't even act different. They just are a little bit slow. To get rid of spyware, download a free, widely acclaimed spyware removal program called Spybot S&D here:
http://www.safer-networking.org/en/index.html
If that doesn't work, it might be your computer. Follow these directions:
1. Remove programs that you never use anymore by going into Control Panel and selecting "Add and Remove Programs". From there, there will be a list that include the programs, software, and games that you currently have on your computer. If you want to remove a program, highlight that program and click Change/Remove. From there, there will be an window that contains the options "Repair" and "Uninstall". Click "Uninstall".
2. Clear your harddrive of temporary files. These files slow down your computer immensely. You can do this by downloading CCleaner: http://majorgeeks.com/CCleaner_Slim_No_Y... After you install this program, start it and press "Run Cleaner". It should take only about 5 minutes or less.
3. Remove Invalid Registry Entries. These also slow down your computer. And guess what! You can remove these by starting CCleaner and on the left side, click "Registry". From there, select "Scan for Issues". It might take a minute. After that, select "Fix selected Issues...".
4. Delete Unnecessary Startup Processes. This is a HUGE culprit on the average PC computer. Ever wonder why your computer is so slow on startup? This is because your computer is loading up programs like iTunes, Quicktime, etc. You can delete these processes with no deletion of the program by using CCleaner. Once you start up CCleaner, select tools on the left hand side and then select "Startup". From here, you can delete startup processes like AIM, RealPlayer, and Quicktime. WARNING: There are no backups to these processes, so if you delete a Windows process, you will either have to reinstall or turn to a professional.
5. After deleting all of those things, you will have a HUGE space in your harddrive. Problem is, it doesn't make much of a difference in speed. To finalize the spaces that you have made, you need to defragment your harddrive. This is a lengthy process, but it works in the end. What you need to do is press Start>All Programs>Accessories>System Tools>Disk Defragmenter. From here, you select your main drive and then select "Defragment". If you haven't defragmented in a while, or never have, it will take a LONG time. Maybe 1-5 hours. But it all is worth it at the end.
This will take awhile, but in the end, your computer could get 50% faster.