MD11 left turn tendency

Hello,I recently bought the MD11/MD11F FSX package, and I installed it on a FSX + Acceleration clean instalation.However, I noted that the aircraft, when taxing, always deviate to the left, forcing me to always make corrections to the right. I thought about joystick calibration problems, but I tested taxing after disable all joysticks (CTRL + K command on my FSX), and the problem continued.I thought that after disable the joysticks, the command surfaces of uncalibrated joysticks may have stayed out of its center positions, and I decided to apply CTRL + K (joysticks off) command and, after, I decided to center all surfaces via keyboard (NumPad 5 command), but the problem continued.So, I analysed the CONFIG screen on the number 4 display unit, and I noted that even after disable all joysticks and even after reset all surfaces via keyboard to its center positions, something was still commanding a little bit of rudder to the left... if I center via keyboard again (with joysticks still off) something continued to apply a little bit of rudder to the left again.So, something is apllying a little bit of rudder to the left, causing the aircraft to deviate to the left during taxi and (of course) inflight too. The joysticks are off, the surfaces were centered but something still move the rudder.I don't use a registered version of FSUIPC, so I don't have access to FSUIPC axis related features.Please, I will be glad to receive some help from you, and except this small problem, this is a magnificant aircraft.Thanks,Marcelo Monteiro