Only Safari Will Connect to the Internet

Hi Techy People,

I have a problem that many seem to have...

Only Safari will connect to the internet... Firefox, IE, iTunes, etc will not.

This problem began when I was running Vista. I thought that upgrading to Windows 7 would solve this but not.

I have spent months trawling the www to try and find a solution.

There is no malware on my PC.

I have got rid of Norton.

I have tried disabling the firewall.

When I upgraded Safari that would not connect... fortunately I had a restore point to roll back.

I cannot install AVG as this needs direct internet access.

I installed Avast today and that knocked out Safari giving a winsok error.

Throughout this I have had an internet connection - can ping through the command console.

Also, note that I cannot uninstall Firefox as I wondered if there was an add-on which had caused this - Firefox was my previous preferred choice before it stopped working.

Does anyone have any ideas other than the 'wonderful' advice that the TechGuys at PC World offered that I 'should buy a news computer'!!!

I am quite tech savvy and as such do not want this to beat me...

Look forward to some great advice...

CJ