Its caused by the "pothole" problem I believe. There are a number of potholes (which are not visible) at numerous airports across the FS
World. These can be in taxiways or the runways themselves, most aircraft will pass over them without any major problems (unless you are trying to stop a 767 on a runway littered with them - you don't really get much brake action), however, the POSKY 747s in general seem at a higher risk of NG
The best cures would be to turn crashes off (which normally works but doesn't appear to for you) or to try getting a new AFCAD for your airport where this keeps happening.
Oh and guys, watch out for 5L
, I barley managed to stop my 767 from an overrun its just potholes everywhere.
Lifes a train racing towards you, now you can either run away or grab a chair & a beer and watch it come - Phil