Sudden change in Pitch (problem in cubase 5)

Hi,

Do you have any midi controller or midi keyboard plugged for instance?
I had the same issue a long time ago, and was caused by my akai midi keyboard that sometimes sended data when recording.
Even when I didnt touched any knob or fader in the midi. Only playing the keys.

In my case it was the Panning.
I workaround by disabling the CC trigger for the panning.