I was setting up the ArcMap connections for a new user and tried to open Administrator to check that the license server IP was set correctly. It would not open at all - twirling blue and nothing. No error msg, nothing. Then I tried Open, then Run as Adminstrator, and still nothing. I thought maybe it was his install. So I went to my desktop and got the same thing. I know mine opened before OK because I had to reset my license server IP. Any ideas?
What has changed in the machine since the last time it worked? Any upgrade or new installation of antivirus? Check if disabling the antivirus helps, or disconnecting the machine from network. The last resort would be to repair ArcGIS Desktop.
I'm assuming you are asking about the Desktop Administrator and a concurrent use license manager? You may want to move this thread to ArcGIS Desktop Installation support which deals more with license manager issues.
Make sure you don't have ArcMap or ArcCatlalog open when you try Desktop Administrator. A reboot might help.
Have you verified that the license manager is running properly and the license manager machine is still reachable? Try opening a command prompt window and Ping the ip to make sure it is still there....maybe just a network issue. Since multiple machines are having trouble, it might not be the desktop clients, but maybe a network issue or the license manager needs a restart.
Although I don't this this is the issue, I know because we have many remote users, (and to speed up license connector) we create and set a system variable as talked about Bug: The ArcGIS Desktop Administrator is unable to connect to ArcGIS License Manager 9.3 when networ... Its mention 9.3, but it helps with our 10.x installs as well.