I installed ArcIMS 3.1 after uninstalling ArcIMS 3.0. Now ArcIMS Manager doesn't work.
Check that the virtual directory has been updated for ArcIMS Manager.
Solution or Workaround
The virtual directory for ArcIMS Manager to point to should be <drive>:\Program Files\ESRI\ArcIMS3.1\Manager instead of <drive>:\Program Files\ESRI\ArcIMS3.0\Manager.
For more information on virtual directories, refer to the ArcIMS 3.1 Installation Guide.