Well first things first have you an up to date Virus Scanner installed?
Do you have any Spy Ware Tools installed?
If the answer to each of these is yes have you made sure that they are up to date and run a Scan in [b]Safe Mode[/b] before you consider reloading the computer?
If you don't have any Spy Ware Tools you can download from the following URLs and install then update and run in [b]Safe Mode[/b]
http://tinyurl.com/du0h
http://tinyurl.com/yrwy2
If you don't have a Virus Scanner you can get a free one at the following URL
http://tinyurl.com/j3dn4
When these are downloaded and installed you then need top update them and once this is finished you can reboot and press the [b]F8[/b] key till you see the Screen to chose which mode you wish to boot in and chose [b]Safe Mode[/b] and allow the system to boot and then run all the scans. If any come up with a problem allow the programs to remove the problem files and then do another scan with the same program just to make sure that the affected file has actually been removed.
Start you the AV and then with one of the Spy Ware Utilities and always run the same application again if there are any problems found.
Once this is finished you can reboot as per normal and run [b]Defrag[/b] to speed up the system and see ho it performs then.
A reload is always the [b]Last Resort[/b] but it's a good idea to [b]Backup all your Data Now[/b] so that you don't lose it if you need to do a reload.
Col