This is what I recieved from Westwood support after contacting them on the same issue:
"We are investigating the cause of the installation issues that are being reported by several Dune customers.....[blah]... the problem across different copies of the game."
They also said that it might be a "security issue" with certain CD-ROMS ("SafeDisc2" ?.. Me not saavy.)... but that wasn't the case with me (3 different CD-roms), and even more so, it definately isn't what's causing your problem.
not much help, sorry
