IME (on systems infected and owned/used by others), some alterations are made to system files which prevent normal use of browsers.
I spent a number of hours trying to clean/restore a system with such and it never did regain ifs full functionality.
I finally deleted the partition and did a clean install My hat goes off to those members who try to resolve malware situations on a daily basis.
FWIW: BC Removal Guide, Malware Defense
NOTE these lines of the guide: "If you are still having problems with your computer after completing these instructions, then please follow the steps outlined in the topic linked below: Preparation Guide For Use Before Posting A Hijackthis Log."
The log should not be posted in this forum, but in the HJT forum.