It seems, as has been said, that if I don't ask for altitude changes en route, I don't have a problem... at least so far.
Otherwise, I just took off from OPRN en route for VNKT. Another airport (Islamabad) where TGS thinks the runway is somewhere in the middle of the parking apron... MakeRunways is doing something odd. And then when I take off ATC directs me towards my filed flight path and then, when I am on it, turns me away again. 15 seconds later, when I am still turning away, ATC comes on again to direct me back to the flight path, a turn of 90 degs by then. The poor virtual passengers! I wish I could get to the bottom of this, as this is in a 'low tech' A310 - no CDU or whatever and I certainly have no SIDs programmed. My first waypoint is 60 miles from the departure airport... Is the fault somewhere in the PFE_*** flight plan? Ho hum ....