Mine did this for about a year becoming more frequent recently. Turned out to be the Engine Speed Sensor (analogous to a cam position sensor). It tells the ECU how fast the engine is turning and without it, the car won't start. Again, that VAGCOM download noted in your other thread will confirm this. Take a look at a recent thread on the subject and note the associated codes numbers: 16705 / P0321 and 16706 / P0322.