Virtual instruments stop playing

[KSband]

I've had recurring problems with a recorded midi keyboard part that will randomly stop playing, I have to replace the synth to get it going again. Today my Xpand2 kept stopping and even after a reload it stopped in the middle of playing a midi section. 

[KSband]

I've had to resort to recording the synth to another track so I don't loose it. I've had the same problem with Sweetcase and the strings Cakewalk includes. 

[David Baay]

Check your MIDI Prepare Using Buffer (Preferences > MIDI > Playback and Recording).  Default is 50ms IIRC. Lower can be problematic and higher may be necessary for some synths in some projects.