How to clean up my computer?

My computer has been acting weird lately, freezing up and missing the little icons in the bottom right of the screen that usually pop up right away (msn messenger icon, weatherbug, avg anti virus…etc.) I tried to do a system restore and everytime i try it says incomplete restore. what other things can i try to make my computer work better (faster, not freeze, etc.)

when i open folders or programs it takes so long to open… how do i make my computer work faster??

i empty temporary internet files all the time, i check for spyware and malware, and i also clean my registry with TweakNow registry cleaner… what else do i have to do?