Windowc CE 5.0 help needed

I have Navigon GPS running on Windows CE 5.0 using destinator maps. Now I want to hack and run another softwares but problem is whenever I turned on GPS it pickup the default destinator software. My understanding is that it is using some kind of initial program which is defined in registry to load as startup program but I am not able to found which program is that. My question is how windows CE knows what program to load at startup and where is that defined?