Servo troubles.

[Glenn]

This should do nothing more than swing the servo back and forth, from endpoint to endpoint. It'll probably hang up for a bit at the endpoints and might even move too fast or jerk around a bit trying to catch up to the program.
If it doesn't, you've got something else going on.
It all boils down to breaking it down to it's simplest form and building it back up again.
Try it and report back...

Well, it swings the servoarm to one endpoint, stops for a while, then all the way to the other endpoint (or near it anyway) and directly start to go back again and repeats everything.

Its not a very smooth movement but it looks ok.