First flight so I may be doing something wrong. Flying from PHNL to KORD, flightplan keyed in, all FMC pages completed etc. Take off 4R, trim doesn't seem to be holding as per the setting from the Takeoff REF page, CG was set from the value that was showing as the current CG.

Climb to around 5,000 ft, engage LNAV and VNAV and A/P. Aircraft starts climbing and turns toward the next waypoint and the A/P disconnects. Re-engage, disconnects again - this continues until I get to around 10,000 ft and then settles down. Climb to FL370, cruising along for a while and it starts again, yes I have a reasonable crosswind, thinking that may be the issue I shutdown ASN and set the weather to clear skies, now there is no wind and still the A/P disconnects.

Any suggestions, as the aircraft is unusable at present.