I'd recommend doing some simple routine maintenence. If you don't have them already, go get Ad-Aware (free version) and AVG Antivirus (free version, unless you have something better). Then give those a run. If you have any viruses or spy-stuff those should get rid of them. And depending on how long you've had that computer, you might want to try running a Disk Defragment.
It would be helpful to tell what OS you're running, though.
And for the Defrag:
Start>Programs>Accessories>System Tools>Disk Defragmenter
(I believe that works for most Windows versions)
The defrag might not help very much, but will probably take the most time.