Ignition problems my 04 alero has power when you turn the key on but it wont turn over... any ideas?

Call GM dealer service and they should be able to give you an idea over the phone. Describe the EXACT problem to them.
This could be a bad keyswitch or a key gone bad. Could be bad switch down on steering coumn which keyswitch actuates. Hard to say. don-ohio

check for broken timing belt / chain
run fault codes to check for crank/cam position sensors
check ignition control module for operation

The security, antitheft, or passlock light is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterperates this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle.
This link may help you find ways to bypass this or fix it yourself.
http://vatspasslockpasskeysecurityhelp.yolasite.com/

LOOK UNDER THE CAR WHERE BOTTOM OF RADIATOR LOCATED YOU WILL SEE A PLASTIC SPLASH SHIELD WITH TWO LARGE WING NUTS HOLD IT IN PLACE.REMOVE SPLASH SHIELD AND YOU WILL SEE THE OIL FILTER. IF IGNITION KEY WONT TURN IN SWITCH MORE LIKELY KEYLOCK CYLINDER BROKEN. OR KEY WORN OR YOU HAVE WRONG KEY IN THE IGNITION SWITCH.

Ignition lock cylinders are pretty notorious for this. You may get the thing to turn by wiggling the key up and down while turning at the same time. I have also had luck in tapping on the cylinder with a screwdriver handle while turning the key. To completely fix the problem, you will have to replace the lock cylinder. GM (AC Delco) lock cylinder kits come with an assortment of tumblers so the new cylinder can be set-up to work with your existing keys.

no there is no lock position for the alero. if the key wont turn the key and or ignition cylinder may be worn out. try jiggling the key as you try to turn it. you may need to replace the ignition switch to repair this. when you do it will need to be programed to the vehicle. hope this helps

THE KEYLOCK CYLINDER FAULTY NEED REPLACING.IT WILL GET TO A POINT WHERE KEY WONT TURN IGNITION SWITCH. TRY ANOTHER KEY IF KEYLOCK STILL NOT TURNING. MORE LIKELY KEYLOCK CYLINDER NEED REPLACING.

TRY THIS PROCEDURE WITH IGNITION ON WITH KEY IN SWITCH.LEAVE SWITCH ON POSITION WITH ENGINE OFF. FOR TEN MINUTES WATCH THE SECURITY LIGHT IF IT TURNS OFF IN TEN MINUTES.TURN OFF IGNITION SWITCH FOR 5 SECONDS THEN TRY STARTING DO THIS PROCEDURE TWICE.IF CAR DONT CRANK THE DEALERSHIP HAS TO REPROGRAM NEW KEY AND IGNITION SWITCH.

Hello. Move the shifter to neutral and then put it into park with more force. Try the key. Forcefully turn the steering wheel left and right. Then Repeat each step with even more force if necessary. Joe

HAVE CAR SCANNED SOUND LIKE CAR IS IN THEFT DETERENT MODE.IT HAS DISABLE YOUR IGNITION SO CAR WONT CRANK.LET DEALERSHIP FIX IT.