These cars do strange things during and after low voltage situations...They also don't seem to like to sit.

You might check to see if you have a parasitic drain...if you do, the resulting low voltage situation could be causing it and/or whatever is causing the parasitic drain could be your problem.

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'03 530i - manual swapped - 425k miles
'06 325Cic auto 115k
'05 X5 3.0 auto 158k
'99 E39 528i 5-speed 130k