Hello and welcome. As I do not have a MAC, I have not used this tool. But I have used their Windows version.
I believe you can get a Demo version here or buy the tool. Then scan with it as you most likely have a browser hijacker.
Home Pageavast! antivirus Mac and Mac+PC Editions
Author/Publisher: ALWIL Software
Modification Date: December 10, 2007
Requirements: Mac OS X 10.4 or higher Avast! Antivirus 2.74
Edited by boopme, 05 August 2008 - 09:11 PM.