Now that I've finally got my laptop back from Sony, it's developed a weird bug.

Both Firefox and Internet Explorer load fine, but once they're loaded they frequently stop responding - "Not Responding" appears in the title bar and the application stops working.

But then it will just start working again. Very strange... while FF or IE is not responding I can still load other programs , which work fine.

Any ideas?

yes. try re-installing both browsers. Firefox can be downloaded from HERE. IE 7 can be downloaded from HERE

Thanks. The problem seemed to resolve itself in the end, after I'd ran CCleaner and AVGAS. I think I'm a little bit twitchy about Vista because of all the bad publicity it's had!