Have a 1998 Chevy K2500. When key goes on ...

Have a 1998 Chevy K2500. When key is turned to on all normal lights appear on dash, but twice now engine will not turn over (you do hear what I believe is the fuel pump cycling). Last time had service man came and it started immediately. First time it started after 30 min of trying to figure out problem. Have no idea of what I did to suddenly make it work. It ran fine, but dash "security" stayed on entire 3 hr trip. On each occasion the engine was cold.

Have noticed in past that when operating truck, once in a while, some dash lights will flash, and on one occation cruise control would not work.