Also, when ID opens back up, the document that I was trying to open comes up, but it comes up as untitled 1.indd when I go to save it. It doesn't remember the file name that it was before I tried to open it.
Please do not post crash reports here. Post them on pastebin.com and post a link.
As for the issue, I'm running CS5.5 and CS6 with no issues at all on Mountain Lion. However, I did a clean install, not an upgrade.
What you are seeing is the recovery file, not the original, if it opens as untitled.
The report that Bob clipped was a hang, not a crash. Does ID actually close on its own? If so, find the crash report and post it on pastebin.com. If not, see Adobe Forums: InDesign CS5.5 Not Responding for instructions on how to generate the hang report and force a crash to get a report, and post them both, then put links here.
Ok. I'll do that. Sorry about the big post earlier.