I had a pop up from AVG the other day and because I trust it implicitly I just clicked on an OK or yes or whatever is was. Next time I turned on my computer it went to an AVG tool bar and search. Bugger! I said to myself and proceeded to try to get rid of it. but it wouldn't go away slowing up my computer in the process. I have managed to now get rid of it and today my Google service is back to normal. So, have you by any chance introduced a new programme that starts up at the same time when you boot? Could be the problem.
Glad to see you've got it sorted Paul. There are many instances where your computer will, when booting up, go off and look for a programme that was there the last time it was on but isn't there now. Many apps will leave a calling card in the tray, so to speak, if the programme was shut down in inadvertently etc: There is a very good programme called "Advanced Uninstaller" which has various 'cleaners' in it. Used with care it will do a good job of easily cleaning out any rubbish that your computer has picked up also broken links can be detected, registry cleaned etc: And in your case Paul, the startup programmes that load when you boot. Excellent and easily used with CARE. You can also do it from the 'Control panel' in Windows but it is a bit difficult for the not so computer literate amongst us.