Many thanks for the advice Jeff, since checked connections are secure (whilst drive inactive) but think I have found the problem. I let the unit reset and popped out the cd (which was a copy of the original). I have since placed the original Navtec disc back in the drive, and all ok - so far. I realise now after browsing and entering addresses using the original cd, it is far quicker at accessing the data, whereas before it had really slowed up with the copy. Guess it was a case of attempting to read a corrupt cd that caused the unit to flip (reboot).

Thanks again,

Will it still be worth downgrading the firmware though to say V23?