my name is pete

I got a Pioneer deh-p2900mp, nothing special, cause my stock deck in my 2002 olds alero ate a cd and won't play any discs anymore. I got the thing hooked up, and for some reason, the thing will power up and work great with the key on without the engine running. But as soon as I start the car, I have power for maybe 2 seconds before it turns off. I though that this problem would have something to do with an antitheft unit, so I ran a new ON power from the fusebox to the deck. I've still got the same problem.

I hope it isn't a problem with the deck or the replacement dinger module (which is a crappo wal-mart thing.)

Any insight would help me out alot! thanks!