I have narrowed it down to the "cof=FORID...." element, but this happens in both IE and FF, and the config file in Firefox is fine Any clues?
Cleared the cache, it turns to normal if I click on a link from Google TO Google (such as spelling suggestions)
Switch to openDNS - maybe your ISP is doing some sort of sketchy redirect from normal Google to a Google Custom Search (where they get the adsense money)
My guess is that you have cookies disabled somehow, and your Google settings appear in the address then.
This is correct. 'custom' and 'client=pub-xxxxxxxx' are the big giveaways. It's a custom Google search page using Adsense. Clicking on the first 4 links, the Google ads, will give money to the person responsible for the redirect.
Im on virgin media, no-one else is reporting this problem and other PCs on the same network dont either. I assume this is a (Very well though through) virus.
Check your hosts file. Navigate to- c:\windows\system32\drivers\etc\ look for a file named hosts and open it with notepad. There shouldn't be any entries besides the localhost entry. A hijacker could be using the hosts file to redirect. Remove the entry, save it and try googling something.