all software installations hang on my Dell Dim 4700 Windows XP

Every software I install either takes 20-30 min to install or never finishes altogether. Itunes, skype, Windows own updates .net framework for expample.

I have installed the Windows 3.1 new installer – but no luck. I have to believe this an OS problem. I have tried disabling Norton – no impact either way.

Can anyone tell me what is going on with XP? It is now so bad that I cannot shut down the pc, because the automatic application of the updates in queue never completes!

Any smarties out there know what is going on?