Use 30 secs reset method. It will solve the problem.
-Turn key to position 2. But dont start the engine.
-Floor the gas pedal for 30-40 secs.
-Release the gas pedal, step on brake and start the engine.
-Drive FORWARD (Not reverse, so make sure you are out of your garage before you attempt to do the transmission reset)

Do this every other month or when the transmission start slamming again.

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2002 X5 3.0 Siena Red
Premium, Cold Weather, Rear Climate Packages, 19" Wheels
Aluminum Running Boards, Clear Tail Lights, Clear Side Markers
Titanium Kidney Grills, Titanium Trunk Lid, Xenon Headlights
4.6is X5 exhausts, 35% Tint, Aluminum Pedals
2005 530I Mystic Blue
Premium Package, Sport Package, Xenon Headlights
18" Sport Wheels, 35% Tint all around
Mods to come: M-Tech Front Bumper, M5 Side Skirts, M5 Rear Bumper
Quad Exhausts, Style 172 19" Wheels