It took me two hours to reach this stage! Pages kept freezing Avira kept turning itself off! I had to keep re-booting which took an age as my PC always takes a few mins to start!
Anyway, changed the time as per your instructions. Everything OK for a day. Then clock fell one hour twenty mins behind the real time. Now it is over 4 hours behind. Changed back using cmd.
I will look in safe mode when I boot up again. Don't really want to switch off again yet as I have things to do.
Ran Malware bytes - no malicious threats found.
Ran Avira full scan - nothing found.
Maybe my PC is just old!!
Thnks for your help!