My 2001 X5 does it also. I finally found out that when all doors are unlocked with the remote it will happen. If I only unlock my driver door with the remote, then open the other doors from the inside manually (not the lock/unlock button inbetween the seats), the problem disappears. I know I will need to get it fixed, but this will at least keep you from having to jump out of your car everytime you want to drive it to close the tailgate. It can be quite annoying to say the least.