This morning, I configured a group policy. After uploading the changed
policy, clicking Apply, and incrementing the version, after 45 minutes,
the Content Server shows the policy with an "Unavailable" status. I'm
getting the same sort of message on workstations that are assigned to
this policy.

So, I clicked on the policy in ZCM, but when I click on the Details
tab, at the top of the screen is a message: More than one content was
associated with the policy. Using the first content file. Now, when I
click the configure button under Windows Group Policy Settings, I get
the Configure Group Policy settings pop-up with the Upload and Cancel
buttons, but the policy never opens for editing. I'm not sure what to
do at this point.