It's more likely a browser hijacking. There are too many to list here, but tools are noted at http://www.doxdesk.com/parasite/
Post in the Security Forum and look for the Anti-Parasite Suite if you don't fix it.
Under Internet Options Homepage, I set my defaut
to my favorite search engine, hit Apply and OK.
It's fine during that one session, but the next
time I power on my system, the Homepage default
changes to another search engine. How can I track
down the offending file that keeps overriding my