AI Crashing, sinking

Hi y'all,I am fairly new to AI but have succeeded in adding 925 GA flights, 150 or so Helicopter flights, and 500 or so military flights, all in separate .bgl files to ease maintenance/addons. These are in addition to the default traffic which is using real skins and real callsigns for realism.I followed one of my helos that was to take off from KNKX, circle around and land again at KNKX. It did well until the return trip when it started circling and just kept circling until it lost altitude and crashed into the ground. In fact, it disappeared into the ground. Other helos do fine, traffic is busy and there is a lot of waiting to get my 2 cents in with ATC. Makes it really interesting sometimes.Also, the helos seem to be sitting on the ground on their bellies as if the gear had collapsed after a period of time WHen I first start the sim, they're fine but at my destination airport, they are sunk into the ground. A restart of FS9 fixes everything. Has anyone esle seen these phenomena with AI?Thanks in advance,dolph