1999 Renault Laguna not starting

hi can anyone help please my laguna wont start the problem i lock the car open the car insert key immob light goes solid then goes off car starts switch car off restart car light goes solid then flashes car wont start lock car unlock car key in light goes solid then flashes wont start unlock lock car starts dont lock car after starting wont start every time the engine does turn over but it doesnt matter what i do either lock unlock start car light will flash car wont start or not flash car starts no rythm or reason to this other than now wont start at all and light flashes every time i try to start car but still turns over billy46