FSX: HELP ! Autopilot stop working in win7

Hi

I have a problem with FSX which is installed in win7. Everything has worked until now. The autopilot does not work anymore. The problem is with all types of aircrafts. When activated a.p. the "nose" dives. Heading, attitude and speed can only be adjusted with 10 at a time (not 1,2,3,4 etc. - But 10-20-30 etc.).
I can still use joystick. I have had the problem before, but have been able to fix it by re-install FSX. I have now tried to re-install several times (incl. sp1 + sp2 + UI.Automation.core file) but without luck. I have checked my pc and found nothing wrong. Does anyone have the solution to the problem ?

Thanks!

Regards

Danair