For all those who offered advice.
Eventually, I tried a system restore in safe mode.
It worked after about 2 hrs muttering to itself.
However, I had this wierd problem with internet access, after initial boot up, it worked for about 3 mins then wouldn't get a reply from the requested website.
Email & Messenger all worked fine.
I sussed it in the end, when I tied to turn off Zone Alarm.
The program would not open, even though Norton Security Centre indicated that it was enabled.
Uninstalled Zone Alarm, reinstated Windows Firewall.
Thanks again to all who offered advice.
Hope this helps if you have just found it in your search.
What year is it now?