Go here and put your log file in the HijackThis log file analyser to find if there is a browser hijacker.

HijackThis is a program used by experienced users in order to detect browser hijackers. It allows you to identify any sort of spyware and malware (as well as some trojan horses and worms). This is achieved by scanning special zones of the registry as well as the hard disk drive, the results being listed in a structured window. Another feature of HijackThis is the creation of a log file, which can be saved as a simple text file and opened by any text editor (notepad as default).

The program can be downloaded for free from here: http://www.hijackthis.de/