Does the problem still exist in Safe Mode?
Yes, it still happens in safe mode.
Well, it's started working again with no apparent reason. Next time it cuts out I'll check that. However, there's nothing unique about it. I've been using the same setup for over a year now. Norton Internet Security 2003 and BitDefender Anti-Virus 10. Norton has had personal firewall enabled, Windows Firewall has been disabled, and I don't use a proxy. Also, I just checked Opera and it still isn't working. So it was apparently an unrelated coincidence that it didn't work. I just rarely use it so I hadn't caught that.
marking wfm in that case