I'm guessing u have already done the following:
> a virus scan with latest virus definition updates
> a spyware scan with latest updates
if not, i'd certainly recommend doing so.
apart from 'Sims' and 'MPIO', have u tried installing any other software? maybe u can try 'winamp' and see if that installs or not
also try turning off ur virus scanner before installation
welcome to TIMO