Can you help fix y reg corsa 1.0 petrol?

Hi, my 1.0 petrol engine corsa has a small problem, when I start it up with the original key it often starts but then dies within seconds I try starting it an giving it sum gas but makes no odds, all the dials just drop as if the ignition is not on. I keep trying but it simply wont start but if I go back a few hours later it starts. Sometimes when Im driving it the dials all drop as if the ignition isnt on again including rev counter, speedo, petrol and temp gauge, but the engine continues to run an still works no probs apart from all the dials, when this happens if i turn the engine off it will not restart untill all dials are back working again. When it is playing ball it starts up first time with no need for any gas an runs like a dream.