Its going to be your script!
But seriously, it IS going to be a script problem so here is a few things to keep in mind.

1> Make sure there is not any other code (like the templates) trying to control the camera un-expectedly.

2> Never change the camera's position or rotation more than ONCE per frame.
If you have more than one function 'controlling' the camera, make them store
the changes into a shared storage location, and have ONE of the functions
apply those changes to the camera just once per frame.

3> Always put a PROC_LATE into the function that moves the camera. (Check the manual under PROC_LATE)

Best of luck, and welcomne.