Macbook Pro asks for wireless password after waking or restarting

I manage a school network of 250 laptops and im having a problem with about 90% of the laptops. When the laptop is closed or restarted it always asks the students to type in the wireless password.

I have checked keychain and the wireless password is saved there.

I have tried erasing the keychain entry and recreating it. That didnt work.

I have tried erasing the System Configuration folder and recreating it. That didnt work.

I put parental controls on the student accounts originally but because it was causing a lot of strange issues like iDVD not working and constant errors from google updaters, i turned off parental controls. I was thinking maybe that had something to do with it.

Any suggestions on how to make the laptops stop asking for wireless passwords?

Thanks