I've just picked up my 06 GTI from the dealers after having the ignition switch replaced under warranty.
The problem was that occasionally, usually under heavy drain on the electrical system - night time, aircon and lights on, then flash the headlamps, put into reverse, etc, I'd get a beep from the dash and then various warning lights would come on (abs, steering, etc) and the radio would cut out. Occasionally the power steering would stop working and the steering would become heavy. Luckily this usually happened when parking, not on the road! Also, I could detect a slight dimming of the headlights whenever I put the indicators on.
The battery seems fine as the car starts easily.

I took it to the dealers as I had a warranty. They said it needed a new ignition switch, and that has been replaced.
Last night when I drove the car, the radio cut out again (but no beeps of warning lights!).

Has this happened to anyone else, and is it a known issue?

I'll check the radio connections (Aftermarket, but all connections soldered).

Hopefully it is fixed, but it seems an odd repair for the symptoms.

Cheers,
Kev.