Ghost Contacts

Hi

I was wondering if anyone can help me with this windows mail issue.
When I use my contacts list on windows mail I get an address that I havent ever used or seen before. When I type R I get a list of my contacts that begin with R. One of these is R.Thompson234. I have no idea who this is. I didnt put them in my contacts list. I dont use MSN and nobody else has access to my laptop. I cannot delete this contact as when I look at the list of contacts it does not appear!
Is there a secret file that keeps all contacts? I cant think of what else to do.
Thanks in advance for any help.