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.