I began to have constant pitch bend messages being sent by one of my midi controllers, and it turns out it is due to cheap components in the hardware of the controller.  Apparently several different brands of keyboards and controllers have the potentiometers that are connected to the pitch bend wheels end up wearing out, and then they start generating random crap that gets picked up by Sonar.
 
For MY situation, I went into edit mode on the controller and I turned off Pitch Bend altogether.  It had been making things play back out of tune anytime I played something on that controller.
 
I used Midi OX (Edited to correct) to monitor the data, but you could also just arm a midi track and hit record and let it run for a minute, and it will capture any of that random data.  Then you can look at the Event List for that track to see what is being spewed out.
 
Bob Bone
 

JCody
OK, I just noticed something on the rig I'm using. Maybe it's in the template but the input has TWO inputs assigned. The fireface 800 midi AND the keyboard. Maybe they're fighting it out and throwing controllers all over the place.

Another possibility is that a MIDI feedback loop has been created.

are cakewalk making sure that templates are backwards compatible with each update? if you recreate the same setup as the template from a blank, do you get the same issue?

I would check if your are sending out MIDI data from Sonar which is echoed back in from the controllers e.g. MIDI clock ... this would be project dependent and hence happen across setups.

I put a thread up not so long back about un-requested MIDI pitch changes occurring. there were a few answers given, and in the end, and after a lot of faffing about it seems that the culprit was/still is my Alesis Q49 keyboard which seems intent on dropping everything I do by a semi-tone (not a full tone as I originally explained I might add) so indicating a fault in it's make-up. Disconnecting it removes the problem from the playbacks although I now have to temporarily rely on a Yamaha 88 note keyboard for keyboard inputs and that takes up a little too much real estate for my liking!

JCody
 
Wow, I just started a midi project and it's been awhile. I find that LOTS of controller data is being dumped into my tracks without even playing anything. Lots of random stuff including Pitch Wheel. I was all of a sudden discovering that my samples were drifting out of tune because of it. The work around for now is to make sure that my input is NOT assigned to the controller I'm using. I've been going to All Inputs ch 1 and then everything is fine. Anyone else experiencing this?

A great little free MIDI utility that can monitor any messages coming from your controllers is MIDI-OX.
 
Watch all MIDI port activity and monitor messages in real-time.
 
Just shut down Sonar and fire this up.  Should rule out Sonar if you still see the spurious controller data.
 
http://www.midiox.com/