Folks,
don't let your dealers fob you off. There are known problems with the mib head units in many of vw's cars. Issues range from screen freezes to black outs etc.
This is a thread from the golf r owners forum
http://www.vwroc.com/forums/topic/12765-discovery-nav-problem/
There are other similar threads on the gti and Polo forums.
Thankfully the dealers do seem to respond pretty well to the problem. Typically they need photo or better still a quick video of the issue, then they can make a warranty claim.
I believe the dealers typical troubleshooting approach is:
1 try a system reboot using their vas workshop system.
2 update the mib head unit software
3 replace the screen unit
4 replace the media unit in the glovebox
As the full unit is about £2000, you can see why vw only sanction that after all other options have been explored.
To be fair I haven't heard of any recurring issues after a replacement unit has been fitted. Also for many the software update has worked, as has just having the screen swapped.
However a dealer saying they havent heard of any other problems is just not right. It might be the case for the Tiguan, but that's just because they are so new. There have definitely been many cases of this issue with the golfs.
Hope this helps.
Axel