What happens when you try to enable the firewall?

It just says "your network administrator is managed by group policy" or words to that effect, strange because my firewall was working ok a few weeks ago.

I found this at another site; Start => Run => Type netsh winsock reset then click ok. Restart your computer then check windows firewall again.
Give it a try and see if it works.

Thanks Crunchie, but no it did'nt work.

I have downloaded a free firewall from pc tools, pc still very slow, but seems a little faster for some reason.