RNS-D rejecting disc randomly...

[Zip]

... went to France and stuck my 2007/8 major roads of Europe disc in to only have it come up as incompatible. Tried a few more times with no luck - thought the laser might be dirty, and occasionally when it gets REALLy hot in the car, the Nav won't start up.

Got home, swapped back to my domestic disc, which only started working after a couple of ejects. Now stopped again. I stuck a laser cleaner disc in, but of course you can't run it through a cleaning cycle.....or can you?

Anyway... anyone dealt with this problem before? I need to get it working.

Cheers,
Zip