>The IT consultant swears that all have admin rights on their workstations. That's the first thing I asked him. But, assuming that they do not, how can any launcher work if only some users can run it?

Religion requires "swearing"/belief. Science needs evidence. I'm dealing with a similar issue now. I'm on Windows XP. The users have a mapped drive. When they launch my launcher it does nothing. Only by going into windows explorer and clicking on the mapped drive does it finally work. This only happens occasionally.

Our network admin didn't swear. He investigated. We're still looking at solutions. I've had ADIR recommended and will have to try that.