This may be a 'bug' that needs patching but have you tried right-clicking on the launch exe then properties. Along the top choose 'Compatability' and then 'Run this program in compatability mode for Windows XP SP2'. I also 'Googled' your problem and found this page here:
LucasArts Technical Support Forums
Basically the poster had the same problem or one very similar and LucasArts posted back with links to updates and possible solutions (with a link to a patch), you'll have to read thru to find tho'
Good luck and I hope this helps

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