glow plug disorder (GPD)

[Blissy]

Sometimes Nelli does this thing where I turn the key to the on position, and instead of the usual clic on clic off sounds she goes cliclicliclicliclic and doesn't stop. THen I turn her off, on again, and she doesn't do anything. After a little break she's okay again and follows the normal procedure.
What is GPD, can it be healed?
There's no control light that tells one the glow plug moment, is there?
blessings