well, after losing my focus thanks to Kaiser's avatar I can now focus on your issue. Basic browser hi-jacking is something simple to address. Assuming you are windows based (again just assuming):
download ccleanr, and spybot Search and Destroy and also Free AVG
Install them all and update them if needed.
Boot into Safe Mode (this is key) This allows only the necessary processes to run so dont be disgruntled to see an ugly or basic interface or desktop once it loads.
run spybot, let it scan...you will notice it will be much faster but let it run its course.. there are close to 40-50k signatures it needs to scan for. during this period, drink some protein...get big.
chances are this is only happening in IE... once done, fix all that is wrong at the end (should be a fix button or something)
Run Ccleanr in safe mode....CLEAN EVERYTHING, and the registry (rootkits are in the registry so this is why you want to run this...when not in safe mode, the keys are locked and cannot be manipulated that are injected into processes.
After all this, reboot into regular mode.. run AVG. Scan and Fix whatever it may find..
This should fix it...if not, download Hi-jack This, run it, and copy and paste your log and i will manually analyze the process cache...