Could be that some other phone is somehow turning on the light. The deletion of the extension should have cleared that. Try the "call sender of oldest (?) message" code and see if it rings an extension in the switch somewhere. If it does - then it should clear the MW light. Again - this may be something that is happening constantly - but at least it might tell you where (what ext) the problem is originating with. Then again I am not a 2000 guy so I could be way off the mark here. But if it were any kind of 200 or 50 that is what I would od.