FSX: Aircraft pitching problem during cruise.?

-I recently re-installed my FSX acceleration. Normally what I would do is reach cruising altitude with the autopilot on, set it to 16x speed (max allowed with autopilot on) and allow the flight to run it's course while I do other things, making sure I keep the ATC contact on.



However now after I re-installed my FSX acceleration and I follow the same steps with ANY passenger aircraft (from the default 737 to the Overland/SMS A380) once I set it on 8x speed, the pitch is continuously fluctuating up and down, along with the autothrottle attempting to balance out.



I have tried re-installing again but it does not change anything, it worked perfectly at 16x simulation speed before but now I do not know what is wrong. Any ideas to fix this anyone??have you tried the video & online games section



cause most people on here know more about the avionics in the actual planes than what's going on w/ your computer