Help with Trial Version Source Clock

I have recently built a new I7 pc with Win7 64 bit OS, and am in the market for a new DAW.  As a long time Cakewalk user, from the old 3.0 to Pro Audio 9 I have been extremely pleased with this company!!  I downloaded the trial version of Sonar 8.5 Producer.  I cannot get the timeclock in project options to stay on "internal" ... it jumps back to "audio" resulting in whacky jerky timing for midi recording and playback. 
 
Am I missing something really simple?
 
Any help would be greatly appreciated as I have every intention  of purchasing the full producer suite.
 
Thanks!!

As soon as you have any sort of "audio" in your project, the clock has to be set to audio. If you've only got midi tracks you can set it to "internal".

And make sure your audio metronome is off. Options->Project->Metronome "Use MIDI Note" will turn off the audio metronome.

Tarsier is right.
Anyway, with audio as timing source it should work as well, and you'll have to use audio timing whenever there is audio in the project.
Maybe you didn't configure your audio interface yet. If you use any audio track you will know if it plays fine or there are dropouts... Ask again if you find any problems.