Have you tried dropping back to an earlier version of VMSpc. I can't make any of the 4.x versions run properly on my set up. I've checked the VMSpc forum on the Silverleaf website and it appears that they are using their customers as beta testers for their newer versions.
I'm running 2.5 and all works well. I would really like to run a 4.x version for the new screen layout but I need all of the gages I want to use to work. No luck with 4.x.
pete
2000 40' Country Coach Magna w/ CAT C-10