Computer boots okay, but then can't launch programs and icons display like a program


TS Rookie
Okay I'm running XP on Dell Dimension E520, I can login into the computer with no problem, but then when i go to launch a program, the egg-timer mouse just stays up, my program doesn't launch, computer freezes up completely, but funnily enough I can still move the mouse. Now when I'm in safe mode, I've done virus scans using avast, malwarebytes, no threats found! I've also run CC Cleaner and cleaned my registry with it but it doesn't help. What more can I do to try and fix this please? I'm willing to use safe mode but no iTunes services work in it, and that's a pretty big problem for me!

So please any help you can give me is valued! Thanks