IE 7 Home Page Problems
From past experience you MAYBE infected with a Trojan by the name 'Spy Falcon' or one of its varients. This trojan can be difficult to remove. There are a number of web sites dedicated to the removal of Spy Falcom.
I was fortunate in removing this 'pain' by running Spybot in SAFE MODE three times. I will try and find the info that I used tomorrow if you are still stuck.
Good luck