you are very right to be suspicious. microsoft does not call people to tell them they have virus.
i suggest that you try spybot search and destroy it is a free program though they do suggest a donation which you are free to give or not give.
http://www.safer-networking.org/en/download/index.html
run the update then run the check for spyware and remove anything it finds. then set it for advanced mode and run the system internal check.
that should get rid of most spyware / virus one of which is most likely causing the access violation
C&onsultant
30 years in nyc computer industry working with PC and networks banks brokerage legal etc.