@ RobDFW and toolow2:
are you both adding the .NET to your builds? lots of programs now require that to run and will give that type of error when its not there. also, it could be a security issue not allowing them to install- you could try the Unlock Phone security hacks in this thread here:
http://forum.ppcgeeks.com/showthread.php?t=5108
its the very first one listed in first post.