Help! "Test movie" isn't working!

I just started using CS4 a couple of days ago. I was just re-acquainting myself with the basics of AS3 with some tutorials, but for no reason I can identify, today I find myself unable to make Flash cooperate.

Whenever I press “Test Movie”, it compiles, exports the .SWF file, and all of the trace statements execute and show up in the “Output” text window… but the window with the stage in it is nowhere to be found! Not on the taskbar, not hiding behind anything, not in the Windows Task Manager! I can track down the .SWF file and run it independantly, but then the trace statements do not execute. What is going on???

Thanks in advance for your replies,