any other weir electrical issues?
tough to remove key? No clunk when removing key? Radio stays on? A/C won't come on or blower doesn't work?
My first inclination is electrical portion of ignition switch has gone bad. Not 100% yet. $10 DIY part if you order online from someone like ************************************************************ or can be picked up locally for $35 from audi dealer.
Do a search on ignition switch and you'll find lots of info and DIY how to R&R.
Good luck