C13 audio track drop out

Mac mini 3G 6 Core i5, 32 MB Ram, I T external USB drive. Audio performance does not show overload… 2 stereo tracks - Bass and drums, solo’d.

Drum track(No FX) drops out. It always plays fine from the beginning, but will not sound further into the song. And sometime s, it will sound again. Moving part to another track does not fix the problem. But it will suddenly play fine for a few measures, then stop again.
But no dropouts in C12. I created the song last year in C12 and it worked fine then.—
Ideas?

Check to make sure you don’t have any plug-ins in a Trial Mode

Thanks. When I solo’d Bass and drums (1 mono, one stereo) I shut down all processing. Yeah, I thought I had a processor hog.
And it doesn’t make a difference if I am playing all 14 tracks or just bass and drums…