"Security error detected, due to suspicious activity found on your computer"
"Please contact Microsoft certified live technicians for help (020) 38050589 (Toll Free)"
If you suspect you have a virus then there is many free anti virus packages you can install, you can also visit a website such as http://housecall.trendmicro.com/uk/ to scan your PC for viruses.
Please see the video below, this shows what you see and hear.
Some free virus protection software is :-
http://www.microsoft.com/security/scanner/en-gb/default.aspx
Or a list is here