I was working on a few Illustrator files when the electricity in our building went out. My iMac computer restarted automatically, but all the apps that were open closed. I went to reopen the Illustrator files that I was working on before the power outage and Illustrator will not open any Illustrator file. The app quits before opening any given file - this is also happening with my CS4 version of Photoshop. I have not checked the other apps that are included in CS4, but I am sure that they will react the same. I opened these same files on a different computer with CS4 Illustrator version and they opened with no problems. I also ran a diagnostic test (TechTool Deluxe and Disk Warrior) on my computer and all seems to be functioning properly. It looks like the problems with CS4 are isolated to my computer. I believe that all other (non CS4) apps are working fine.
I ended up uninstalling all the Adobe CS4 apps, then I reinstalled them. I tried to open both Illustrator and Photoshop files and both apps still quit before opening any file. Both Acrobat and Media Encoder seem to be working fine. These apps open and also seem to be working correctly... CS4: InDesign, Media Player, Flash, Fireworks, Dreamweaver, Device Central, Bridge.
I don't know what else to do, and Illustrator is something I must be able to use every day.
In case this helps, here's the error message I get when I try to open an Illustrator file:
Process: Adobe Illustrator 
Path: /Applications/Adobe Illustrator CS4/Adobe Illustrator.app/Contents/MacOS/Adobe Illustrator
Version: 367 (14.0.0)
Code Type: X86 (Native)
Parent Process: launchd 
Date/Time: 2009-12-11 16:37:16.821 -0600
OS Version: Mac OS X 10.6.2 (10C2234)
Report Version: 6
Interval Since Last Report: 82873 sec
Crashes Since Last Report: 17
Per-App Interval Since Last Report: 29 sec
Per-App Crashes Since Last Report: -18
Anonymous UUID: 0D957537-3730-4662-8D97-5C5CF0259C5B
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000000ffffff5a
Crashed Thread: 0 Dispatch queue: com.apple.main-thread