After going into Document Setup with a document open, and changing the document orientation from landscape to portrait, InDesign CS5 crashes after clicking OK with an error message (see attached screen shot). I've deleted the settings file by starting ID with Shift+Command+Option+Ctrl held down. I ran some maintenance using the app OnyX (cleared caches, repaired permissions, etc.) Any idea what would cause this? I've stopped short of reinstalling, but that may be the only option. Also, I updated CS5 with the latest updates, and that didn't fix it either.
At this point you may have corrupt recovery data that is preventing ID from starting if it crashes each time you try to launch it. Move everything out of the InDesign Recovery folder intoa safe place (you'll probably want to delete it later, but you don't know yet) and see if ID will launch. Then try opening any files that you were working on at the time of the first crash. Hopefully they aren't damaged and you've only lost work since the last save.
If you have a crash report, pleast post it on pastebin.com, then put a link to it here.
In addition to the crash report, there should be a reason in the ~/Library/Caches/Adobe InDesign/Version 7.0/en_us/InDesign Recovery/ProtectiveShutDownLog.