Truck wont start!!

[squint]

Last night I went out to start my truck and had the oddest experience..

I turned the key and everything was fine.. i heard the engine fire so i let off the key and it did not quite start..

I turned the key again to finish the job, and all I got was a "click" ...

its acting like the battery is dead.. but I dont think it is.. The lights and everything come on full brightness.. but when i turn the key they go out completely.. there is no way that I can see that the battery would die like that?..

Any ideas.. started messed up?.. short somewhere??

I am just about to go take another look and see what I can find.. but I am pretty stumped..