Did you happen to install any video codecs since "the other day"?  I help out in several flight sim communities as well, and one issue that has plagued those communities is intro-movie crashes/lock-ups/black-screens.  Many of the problems have been traced back to users having installed a video codec called ddfshow (which comes with many video codec packs including software like DivX etc.)  Once the offending codec was removed those game installs resumed normal operation.

Of course you could just un-install and re-install.  There was a known issue with the "tutorials" causing crashing so a reinstall would fix any corruption within the game files (if that in fact is what happened).

thanks,

the Monk

EDIT: I just re-read your OP and since you "didn't change or add anything to your system" please disregard the first part of my reply! 

i figured it out. My onboard sound was enabled and i have a sound card in too. I disabled on board and the game runs now. its a little choppy but it runs. I think i need more memory.