I am unable to update the Admin - Site Settings because of an error that reports a null value cannot be inserted into the default langauge field. However, there is no value in the default language field and I am unable to enter one. It is an empty listbox with no text entry allowed.

I am using version 5.01.02, which was the version most recently available for download. Unfortunately, it does not appear that there is any documentation specific to this version as many of the instructions for where to change things in the available documents do not match what is available in the version I have. For instance, there is no Host language section and no Host skins section, despite the fact that the Quick Administration Guide describes these locations.