I have no idea what I've done (other than install the TrackIR Vector Enhancement) but none of my PDG 737NG aircraft will work. Sometimes I get a 'beep' when I try to select an aircraft, other times it locks FS2004! Oh the only other thing I did was delete FSUPIC.DLL because it gave a long error message and crashed FS2004 before it started (but I have no use for it anyway).The screenshot of task manager is attached. Can anyone help please?

You might want to delete the FS9 cfg and let FS9 rebuild it the next time you start up the sim. This has solved a lot of problems for me (and this possible fix is also mentioned in the PMDG manual).Ricardo

Thanks for the suggestion - that's the one in documents and settings...FS9 ?Dave

OK this is now fixed and for reference if anyone else has the same problem ... the cause was FSUIPC.DLLOriginally this file caused FS2004 to crash so I deleted it. Some aircraft (especially the 737NG) NEED this file.I did a Google search and downloaded the up to date version and 737NG works as does my Airbus autopilot now :)DaveW

FYI: The documentation clearly states that FSUIPC is needed for the NG.