Hangers dialog won't open:

Unhandled exception has occurred... Object reference not set to an instance of an object

Continue button is Grayed out, and I cannot proceed with my calculation.

No Ribbons / only the HydraCAD Ribbon appears, and no commands work.
Revit could not complete the external command. Could not load file or assembly. The system cannot find the specified file. 

The View button that appears after running a calculation does not do anything

One or more toolbars cannot be found after selecting a menu or command.

This happens because the toolbar is being opened 'off screen'. This usually happens when the computer has a dual monitor but the 2nd monitor isn't currently connected. 

Printing a calc shows this error in HydraVIEW;

File not found Runtime Error 53

When trying to open a calc job using [File|Open], you get a Run-time error '62': Input past end of file

When selecting Adjustable Ring Hangers for pipe sizes larger than 8" the detail does not show.

While in your viewport, your riser is visible while in the 2D Wireframe view.  However if you change the Visual Style to Conceptual or Shades of Grey/Shades of Gray, your 3D riser disappears.  You may notice if re-appears if you zoom out.

After printing your data in HydraLIST, when HydraVIEW opens you attempt to change the default printer. 

You get an error "Page Setup - Unknown filetype found 'HLTF'"