Sounds like a virus or malware. I would do an online scan with this:
http://www.pandasoftware.com/activescan/com/default.asp?IdVendor=1&IdLang=2&IdPais=63
I would also download and install this:
lavasoftusa.com
Download and install adawareSE..
http://www.pandasoftware.com/activescan/com/default.asp?IdVendor=1&IdLang=2&IdPais=63
I would also download and install this:
lavasoftusa.com
Download and install adawareSE..