I've had the same problem on two occasions on my May 07 R56MCS, which also has SP01 run flats.
The car slipped sideways, thankfully without crossing the white line and none of the electronics seemed to be activated (I have
DSC). (dry road, moderate speed, light acceleration)
The rest of the time the car has been rock solid, though it isn't fully run in yet.
I've always been planning to change the wheels as I don't like the ones it came with, so am expecting the new wheels with non run flat tyres to solve the problem.