Does the splash-screen say "MIR Pro ready", or is the MIR-logo fully displayed after launching VE Pro? The former case would indicate that there's something worng with the license (... did you install all the latest eLicenser-drivers already?).
Assuming that the license itself is not the problem - can you open MIR Pro's GUI from the "View"-pulldown in the main menu bar?
/Dietz - Vienna Symphonic Library