What the hell is a signature?
If you are geting that error message, here is how to fix halo 2
1. Go to OS(C:) folder
2. Go to windows folder
3. Go to a foler in windows called inf
4. Then once inside that folder, search oem"."
5. Then, either delete all of these files in here, or place them somewhere else
This worked for me so I hope this helped