[mothered]

1. antivirus deepscan
2.ccleaner - startup items review
3. reset your host file
4. check your primary / secondary dns servers make sure they are safe and well known for example 8.8.8.8    8.8.4.4    is googles dns 
5. spybot search and destroy
6. if still having issues comb through with hijackthis for malicious or unknown BHO`s as that could be the reasoning.
7. reset the browser

Do note that this thread Is almost 5 years old.

I'd say It's extremely safe to assume, that the OP's concerns have been resolved.