My recommendation would be to contact Adobe, since they have the ability to walk you through some troubleshooting steps. But it looks like they've already thrown it to us!
1) Have you manually gone to Windows Update and ensured you have even the non-critical updates (which can include important drivers)?
2) Have you manually gone to the ATI or nVidia sites and ensured you have the latest drivers for your graphics card?
3) Have you cleaned your temp files and defragmented your drive(s)?
4) Have you ensured that the program's licensing has not corrupted? http://forums.adobe.com/thread/542377
Finally, you say the program won't launch. At what point does it fail? Do you get a Welcome Screen? Does it only fail when you try to open yesterday's project or does it also fail if you try to start a new project?
Another other details you can provide could also be helpful including: How fast your processor is, how much RAM you have, how much free, clean defragmented space is on your hard drive(s) and if you are editing on your C drive or if you have your media and project files on another drive.
