Thought I might as well add what I get, since there are similarities and it may help pinpoint problems.
I run Vista 32bit Home Premium, the game has always started perfectly - but the intro movie does not play. The sound of the movie does play, but it's just a black screen. Clicking skips the intro without any problems. The credits movie does play without any problems however.
At one point the intro movie did play perfectly, I'm not quite sure what changed.
Hope that helps!