Thanks for posting.
What version of Windows are you currently running FileMaker Server 11 on, and were any updates made on your server recently?
Have you checked the permissions on the both your default folder and the alternate folder path you are using?
To check the permissions, navigate to filewin:/C:/Program Files (x86)/FileMaker/FileMaker Server/Data/Backups/. Right click the backups folder and go to properties. Click on the security tab, which will list the groups and usernames. Make sure the administrator group has full control enabled. Next, make sure the folder has the “everyone” user group. If the “everyone” group is missing, it can cause a folder path not validate in the admin console.
We're using Windows 7 Professional. No updates were done to the server, not even to Java. I intentionally leave it as untouched as possible ;)
I peeked at the permissions mentioned, and all seems well. Administrators and Everyone have full control of the folders.
The odd thing is FileMaker Server apparently does have access to the filepaths it says are invalid, as the backup files are still being updated as expected, even though the Admin Console says the path is invalid and that the last backup was 7/4/2011. The Schedules are apparently running correctly, it's just that the Admin Console thinks the last successful backup was on 7/4/2011, and that every filepath is invalid ;)
Here's a clue though: I see in the Event Log entry for 7/4/2011 a Warning saying:
Administrator "fmsadmin" no longer responding; connection closed. (192.168.0.192)
Event ID: 628
Could be coincidence, but it looks like after this event, the Admin Console stopped reporting the status of the Schedules correctly (it still thinks 7/4/2011 was the last good run), and it thinks any and every filepath is invalid, lol.
I'm sure a reboot would fix it, I was just hoping to find an easier fix without needing to kick everyone out of the system.
Aha, using "fmsadmin restart adminserver" from the command prompt fixed it! The console now displays the correct schedule information, and pathnames are marked Valid once again :) Still no idea what happened to make the Admin Console report incorrectly, but at least there was no downtime for the users to fix things...