PC acting strangely

[aspen]

My Dad's 3 year old dell pc has started acting strangely recently and now its bloody useless. It started off a couple of weeks ago when trying to run some applications or open another IE browser would result in nothing happening. Restarting windows got rid of the problem. Now it is doing it all the time, I can't get it to connect to the net, I can't open Norton to run a scan, open applications don't show up on the task bar. My Dad recently downloaded magicdisc and had some trouble with it but eventually managed to uninstall it. Could this be related?

It takes an age to boot and won't even shut down now, it crashes on the 'saving your settings screen' and there are always a few applications that are not responding.

Does anyone have any advice?

[aspen]

Thanks for the replies. I tried to reply a while ago but I've just realised it didn't work.

Eventually sorted it out by doing a system restore to a date a few weeks previous. Now its running well again.