Since installing ArcHydro (for ArcGIS 10.3), ArcCatalog 10.3 crashes once I try to open the toolbox window. I have reset the application profile for ArcCatalog, ArcMap, and ArcToolbox and it has not solved the issue. I have also uninstalled and reinstalled ArcHydro several times, even in different locations but ArcCatalog continues to crash.
How about repairing ArcGIS Desktop?
What do you mean by repairing ArcGIS Desktop?
Start the setup.exe from the ArcGIS Desktop installation media. When prompted with the option of Modify/Repair/Remove, choose Repair and follow the steps.
I tried it but it didn't work. Thank you for the suggestion!