Cannot Add Missing Account Address

I added a new account for a constituent that I did not have an address for at the time. I am now trying to edit the record to add the address, but the system keeps freezing up or giving me an error. How do I add the address

The reason that the system will not let you edit the address is that there isn't an address record to edit. What you will want to do instead is select Address from the toolbar and choose New address:

This will activate the New address fields on the account screen:

Select the address type by clicking the drop down arrow to the right of the field. If this address should be the primary address, click the box.

Click Continue. The Address fields are now available:

When you have finished entering the address, click Save to retain the changes.