Two possibilities:

1. The arrow keys are pressed (or the computer thinks they're pressed due to a defect in the keyboard (you'd be seeing problems in any text-editting program with this being the case).). Try tapping the two arrow keys and see if it helps.
2. Check to make sure you don't have a code that always does camera.pan += number*time; or the related.

If otherwise, what version and edition do you have?

"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip My 2D game - release on Jun 13th; My tutorials