Have a project in X2 that I was trying to mixdown to stereo...multiple crashes on multiple attempts, so I froze all synth tracks
and audio tracks and increased latency and buffers to allow for a smooth mixdown. 
 
Now the project loads but hangs on the first click. Subsequent clicks get (not responding) message. 
 
X2 will play other files.
 
Fearing corruption and hoping for salvation !
 
Thanks for reading !
 
i5 Quad @ 3.0 
4 GB RAM
X2 PE
UA 25 Interface

Chris . . . will the project open in safe mode ? (open while holding down shift key - to find out if a plugin is causing the issue)

Thanks, Noynekker....I tried your suggestion and the project opened in safe mode but would not play. I can scroll 
in Track mode, but a second click triggers a "not responding" notification.  
 
Am wondering whether to uninstall and reinstall. I suspect though, that it's a file issue, since it played another project without a problem.
 
Thanks, and keep those cards and letters coming. I'm clueless.

Try clearing the picture cache. If you have versioning or auto-save enabled use a previous version of the project.

Thanks, scook...emptied the picture cache, but it didn't make a difference...project loads, but locks up as soon as you click in it.
 
good advice about the versioning and auto save...we live, we learn. 
 
Going to try Cakewalk support tomw....maybe they can suggest something.

Check playback and record timing masters in Preferences > Audio > Driver Settings when project is open.