PSS 777 Autopilot

I have installed the CD version of the PSS 777-200 together with the patch in FS2K2.However I have a problem with level flight. When reaching cruising altitude with the autopilot engaged - Either on LNAV or HDG hold and altitude Hold. The aircraft will start to swing the nose constantly from left to right and pitches also constantly up and down by approx 100 feet margins.I am using real weather settings and had installed FSUIPC 2.86 and now FSUIPC 2.87. No Change.It looks if the autopilot is correcting to much and or to quick.Any suggestions?I have submitted this also on the PSS forum but so far no posting or reply.My PC Spec:Processor Intel P4 1.7G on a true Intel Motherboard.1Gig of Ram - bus speed 400Video Card: GForce 2 MX400 64MBSound Card: Creative Soundblaster Platinum 5.1Controls: MS Sidewinder 2 Force Feed BackMonitor: Samsung 17" 750 SeriesHD: High Speed 20 Gig.