Hi Iain
I am also having this problem and can only find reference relating to a protection circuit which switches the TV off to prevent any further damage being caused. There is a kit called 40WHREPKIT, don't know what it consists of or where to get one from or how much which would reset the fault but then its finding the root of the problem which caused this to happen in the first place. Another site had reference to resistor R821 and diode D802 and transistor but no reference to which one, would fix the symptoms!
Keep you updated if I work it all out, hope you'll do the same
rob, October 2006