Premiere Elements timeline stops moving/playing

Hello,

Hoping someone can help.  I installed Premiere Elements 15 recently and everything has been working fine with the exception of a few "quirks".  Occasionally the "play" button does not move/work in the work area, and as a result the timeline will not move automatically.  I can only move the timeline by hand. 

Some observations: 

When I boot from a shut-down computer and open up a .prel file, the timeline plays just fine using the play button.  If the machine sits idol and goes into sleep mode/, when I click the mouse to turn things back on, the timeline/play button no longer work.  All other functionality appears to be fine.  If I then exit and re-start the program, the timeline will not move at all, and the only way to correct is to reboot the whole computer.

Also, I have noticed another trigger...if I have rebooted and re-launched PE, all is fine with the play button until I use Pan/Zoom.  As soon as I do, and go back to timeline, the play button functionality no longer works. Again, everything else works, but I have to reboot whole system to correct...closing and relaunching is not sufficient.  

Very frustrating and any input is appreciated!

Thanks,
Pete