I checked the system requirements and I should be able to run the game although just barely.

I installed the demo to check this in practise, this is what happens:

The game starts. The video flickers between the shots of the ship and the intel logo. I push escape and I get to the main menu. I quit because of real life.
Later I start again but the game always freezes up (doesn't respond) on the 'credit screen'. It does this every single time I try this.

What could be the problem? why did the game work on the first try?