When I have an issue like that I use MSCONFIG first and then if that doesn't note it I pull out power tools like HIJACKTHIS and AUTORUNS.
I've been having a lot of trouble with upgrading AVG Free. The upgrades would not work unless I fully uninstalled AVG and I did so with the AVG Removal tool last night. Everything worked good, the new version of AVG went in, and all was well. A lot of frustration was expended getting to this point.
Well, today I start up my computer and AVG Remover runs again! Of course, in doing so it removed the brand new installation of AVG Free and now I just did another restart/uninstall/restart/install dance to get AVG Free back onto the computer.
I've searched high and low for processes or services to turn off or remove to get rid of the AVG Remover Tool (the exe went into the recycle bin last night) and I cannot find a thing.
Please help, I really don't have the patience for this as a daily routine.