Greetings!
First I'd to say X3 is working great for me (thanks much for the Aria player fix!).  However, there's a click whenever the tempo changes.  Makes for some interesting rit's (can't write the actual word it gets flagged) in my symphonic stuff:-)  Never encountered this before.  Any thoughts?  I mute everything, it's not there.  I un-mute any track, it's there.
-rich
(X3c build 239)

Wrong forum. 

Thanks!  I would not have figured that out :-)
 

Tempo-related clicks are usually caused by tempo-based effects such as delays.
 
If that turns out to be the case you can work around it by switching off tempo-sync, either for the entire track or temporarily, via automation.