sometimes when i press 1-6 on the cd changer to change disk the music goes off and displays 'mechanic' ??? WTF ? the only way to listen to a cd after this is to go to the boot take out the cartrage and stick it back in, but within a while it happens again ?? whats the problem

Dust in the changer. Remove the magazine then carefully blow into it and vacuum around inside.

Cleaning CD may also help in conjunction with what Phil said

mine does it every so often, just do as above and it works