I can open files and create new ones. But the play and record functions have stopped. Has the beta run out?
No, the beta will not expire for many months. This sounds like it's simply an audio device configuration issue.
Simplest way to test and fix would be to launch Audition and open Preferences > Audio Hardware. Change the Default Input and Default Output options to anything else, click OK, then repeat selecting the desired input and output ports. You can also just hold down SHIFT while launching Audition to override the old preference files and rebuild them with their default settings.
Do you know if you've performed any OS X, Quicktime, other updates, or installed any new hardware that might have affected the audio configuration?
I tried changing the inputs and no luck, BUT...
Shift on launch did the trick! Thanks so much!
And, no I haven't added or changed anything lately. The only thing was I unplugged my USB adapter last evening and the next time I opened the program it would not play or record - although it said it was playing/recording at the bottom left of the page.