I have been receiving emails from my contacts saying they are getting links to porn sites from my computer as 'instant messages'....I know it isn't me and the program hasn't been used/opened for weeks.

Googled around and found this is not...
I have been receiving emails from my contacts saying they are getting links to porn sites
from my computer as 'instant messages'....I know it isn't me and the program hasn't been used/opened for weeks.

Googled around and found this is not uncommon but cannot find any real answers as to how to stop this. Maybe this has been brought up here before but didn't find what I was looking for. Can someone lead me in the right direction? TIA