kyoshi

I have a 2000 Z71 Siverado. The other day the truck was running fine. I parked it and about 15 min. later tried to start it. When I turned the key all the electrical went completely dead. I turned the key off and about a minute later the power came back (security light came on). When I tried to start it again the same thing happened. The electrical power would stay off for 1 to 2 min. each time. Finally the truck started and ran fine. This has happened 1 other time but it started on the second try. The battery if fine and the connections are tight.