Thought I'd pass this along. Couple times over the past month or so my PC encountered a routine called trojan.dropper. I guess this puppy is suppose to drop a trojan on your computer and gets in via infected websites you've visited.
I think my AVG software somehow impeded it's execution but in doing so my browser started acting up.
To make a long story short a McAfee scan didn't find it, AVG scan didn't find it, Malwarebytes found it but didn't clean it up 100%. I was still having browser issues. So, I did a little google work and downloaded spybot which found two fuc'd up registeries and successfully cleaned them. Problem solved.
Just something to add to your kit.