one of the prologue missions will not reload if it is failed on the first try, I have surmounted this simply by winning, however the same crash (screen blanks out and game crashes just before entering hangar) now occurs in the mission in which I need to ambush the Viraxo yacht. This would be okay if at least the game would allow me to attempt the mission but it crashes on the first try! what's wrong? old computer? bad video card? buggy game? Help I am stuck in the lower levels and cannot ascend!

well, first try a drier and game re-install

then if you still have trouble, lets see your computer specs