Resolved WIN xp runs slow; ok in safe mode

Trying to help someone get their comp back to normal in a different town. They have Win xp, sp3. I had loaded av for them and somehow the av got deleted for several weeks. The comp got to the point of not loading browser pages, etc. I had them reload Avast and they have run the boot scan and the regular scan in safe mode numerous times. They can get online and use IE fine in safe mode, but not in regular mode. They have run Malwarebytes and AntiSpyware many times and cleaned alot out, also. Things still don't run after a regular boot up. Malwarebytes mentions something about system32 svc host.exe problem.
Where should we go from here? thanks

 

Thanks. I'll get to work on the list and move posts.