Here's a weird thing that's making me nuts. If I've copied text from say, TexEdit for example, to the Mac clipboard, when I return to ID CS5.5 the Paste command is dimmed. Like there's nothing there. If I copy from inside of ID it works fine, but for some reason pasting is disabled from outside apps. Anybody experiencing this? FWIW, I've trashed prefs. Wondering if it's due to some plug-in I'm running? Hmmm.
I'm on a Mac, with no such problems in 5.5
What version of Mac OS X are you running? When did it start? Was there anything you installed, or did about the same time it started? (And of course you did a complete shutdown of the computer, right?)
Look at this article by Adam Engst. It doesn't specifically mention your problem in his article on 10.6.8 problems (none of which I have).
But a suggestion is to use the 10.6.8 Combo Updater. Perhaps you had a bad 10.6.8 install.
I have just had exactly the same problem using CS5.5 (Windows). When I quit the program and restarted the problem still existed.
However, when I rebooted the PC pasting seems to be working again.
Very strange ...