Are you updated to version 7.5.3? What OS?
Any error message?
Create Suite 5.5
Have you run Help > Updates to get the version 7.5.3 patch for InDesign?
Do you see any error messages?
You probably have a crash report on the Mac. Please post it on Pastebin.com and give us a link to that page here.
note on crash
Process: Adobe InDesign CS5.5 
Path: /Applications/Adobe InDesign CS5.5/Adobe InDesign CS5.5.app/Contents/MacOS/Adobe InDesign CS5.5
Version: 22.214.171.1243 (7530)
Code Type: X86 (Native)
Parent Process: ??? 
Responsible: Adobe InDesign CS5.5 
User ID: 501
in order to get any clue, we need to see the entire crash report. Please post it on pastebin.com, then put a link to the page where you did that here.