There may be a lot of rubbish running in the background that you don't know about and don't need.
Click Satrt / Run and enter msconfig in the box and click OK
Select the startup tab and see all the programmes that load and run automatically at startup time - I have the top 4 selected - you decide what you need.
Next get hold of Spybot Search & Destroy (free) and use it to get rid of any malware it finds. Run it weekly.
Consider an alternative Browser like Firefox (free)
Get hold of Piriform's CCleaner (free) and use it to tidy up the registry on your machine
Defragment your disk.
All this may take you an hour so you need some patience.
I do not guarantee that this will solve your problem but you'll feel much better after doing it.
Good luck...
Peccavi
March 2009