Intermittent starting problem

Can anyone help ? My N reg disco 2.5tdi intermittently will not start. Have checked all earth straps, has a new battery. Most recently, when it won't start it has melted the plastic casing around the handbrake cable. The rear windows will also sometimes not open. Not sure if this is related to the starting problem. Cannot pinpoint why it does it sometimes and not others. HELP !!

Its an earth problem,check them again and maybe add an extra one twixt body and engine.Your back windows are down to a failed soldered joint in the window lift ECU up under the passenger footwell.(if its RHD)Take the circuit board out of the black plastic box and look closely at it,you will see one burnt joint.Resolder it and all will be well.

Not starting as in it wont turn or as in it'll turn but wont fire? If it aint turning then like eight said, most likley a dodgey earth somewhere.