Autopilot / FMC problems

Hello,I have had the PMDG NG 737 for a couple of months now. Running FS2002 on an Athlon 2000, 512Mb Ram, win 98 se. I spent several weeks following Metzinger's tutorial, having lots of fun and with no real problems. [i did find it was necessary not to touch the speedbrake lever at all prior to take off, even when reset to the hard detent position it would cause the take-off-out -of-config warning horn to sound.] Apart from that everything was fine till I returned, virtually, to the UK to begin line flying. First time I connected to VATSIM with the PMDG 737..... problems. On take off, when I hit the TOGA hot spot, the throttles advanced to about 45% N1, then stopped. I found the only way I could get take off power was by disconnecting the A/T switch, and using manual thrust setting. After take off, when I selected A/P, L/Nav & V/Nav, with the FMC carefully confirgured, all kinds of odd behaviour followed. The A?P started inventing some very strange turns. (The EFIS was displaying the flightplan in solid magenta, then it went to broken Magenta for no apparent reason) Tried using Heading hold, but this was even worse - steep uncommanded rolls etc. Would not even attempt to capture heading. V Nav was equally frighteining. We spent several minutes pitching up & down before I switched the A?P off and flew down manually for an emergency landing. I think the VATSIM man was wondering what I was up to! Not to mention pax!Today I tried flying the same 737, offline, but both the A/T / TOGA & A/P were up to the same tricks, and the aircraft had to be hand flown.Apart from that the PMDG is an excellent product, and I look forward to getting this glitch sorted. Can't think of any other factors, apart from VATSIM, which were new when the problems appeared. But then why are the problems still there when I did not have Multiplayer, SB running?Any ideas?CheersNeil RitchieCardinal VA EGKK