My Firewall keeps shutting off, right after I try and turn it on. No error messages or anything; McAfee even says I'm secure even though I I'm not. I've tried uninstalling it and that hasn't worked.
Run the Virtual Technician http://mvt.mcafee.com/
If that fails to help it's possible you have spyware that has sneaked past McAfee, it can happen as no antivirus is 100% guaranteed.
Run the free version of these two tools after updating them: