Originally Posted by mort
This issue might be caused by a corrupt 'cookie' (a file) put on to your system by Sheffield Forum. You need to remove this file manually.
In Internet Explorer do the following:
Click Tools in Internet Explorer > then Internet Options > click Settings in Browsing History section > then View Files. Find and remove files with 'sheffieldforum' in them.
In FireFox do the following:
Click Tools in FireFox > then Options > then Show Cookies - in this list search and remove cookies with 'sheffieldforum' in them
Please try this and see if it resolves the problem.
If it doesn't then there is a good chance you've picked up some malware
Thanks for that and tried it but makes no difference......so as you say a malware infection.