Hi Simon. I have an '03 996 C2 with an extended warranty. I had the CDR22 radio replaced last year at OPC Cardiff as it was behaving like yours. Sometimes I would start the car and the display would just say "Porsche" - you couldn't do anything with the radio - no sound, nothing. I would have to pull over, lock and unlock the car and start again - it was fine then! In short, I called OPC and they replaced the radio under the warranty. (I bought the car second-hand from OPC, so it had the extended warranty. Out of interest, the warranty was in its' third year - the two years which Porsche supply had elapsed) All was well for a while - but I'm sending the car back to OPC on Thursday this very week to get it looked at again!!! (Maybe these radios are all set up to go wrong at the same time!?) On this occation the problem is that the radio sometimes cuts out altogether when I go over a bump. It then comes back on at a different station. This has worked out well sometimes as I have been bored with the music I was listening to anyway. Now I'm no mechanic, but I reckon that they haven't put it in properly (sic). I just hope that they are more attentive when it comes to more serious problems - like remembering to put new oil back into your car before they take it off the ramps, etc. Anyway, call your OPC and get a new radio. Job done. Take my advice, try NOT to start your conversation with, "I'm not sure if it's covered under my warranty, but....." If you get any static just go straight to Porsche UK. This usually doed the trick. Best of luck!
Adrian.