Problem connecting to network: "com.apple.parentalcontrols.keychain"

Hello there, this is my first time posting a question.

I have an iMac, 2.8 GHz, Intel Core 2 Duo, 4 GB memory, 500 GB storage, running Mavericks with everything updated.

I recently had to reset my Airport Express. I tried to join my existing network, and I received a popup:

Keychain "com.apple.parentalcontrols.keychain" cannot be found to store "[my network name]"

It gives me the option to Reset to Defaults. When I clicked Reset to Defaults, it says:

Are you sure you want to reset your keychain? This will delete all your saved passwords, keys, and certificates. You cannot undo this operation.

When I click Reset, it asks me to enter my login password to create a new keychain. However, it does not allow me to enter anything into the text window.

After going through the sequence above (even though I run into a dead end), the computer does indeed connect to my network and I'm able to use it. But it disconnects anytime the computer goes to sleep, so I have to go through the whole sequence again each time.

The Airport Express and the network are working fine -- when I connect from any other devices there is no problem. The appears to be a problem with the keychain or the Wi-Fi on the computer.

I have searched the support forums for "com.apple.parentalcontrols.keychain" and found many things relating to Time Machine set up. But I couldn't find anything on Apple Support OR the web having to do with my edit. I also called Apple Support and tried to pay $20 for tech support and they wouldn't do it because my machine is too old (2007).

I tried one thing: I went under Settings > Network, and deleted the Wi-Fi option. I then clicked the "+" sign to add it back. Someone online said that tends to fix most Wi-Fi problems, but it didn't fix mine. Of course mine is probably a keychain problem. I'm a little afraid to mess around with the keychain for fear of losing all the passwords, so I haven't tried anything yet.

Thanks,

Flossy