You did the correct thing when you tried "to test how well this runs on windows 7 before i buy it". As mentioned in the "Try before you buy" pinned thread: "--- a trial is highly recommended, to check compatibility with your system----".
Thank you for your help. Got it working. Seems i missed some .NET framework updates. The program was trying to start without the license window popping up where you could pick the trial period and registeration.
It works ok for my system. No crashes or hickups yet.
Only thing Vegas studio platinum did not like was when it scanned my VST's folder and flipped out and crashed. Solved by renaming my VST folder for something else for the first boot and replaced the regular VST folder in settings to some temp folder. This has been the case since i can remember (same thing in earlier vegas versions).