When opening HydraCAD you get the error;

Exception in hcadmainbase.arx ARX Command

Unhandled Exception c0000027 (c0000027h) at address aca746e7h

Drawing Setup dialog doesn't load

No error but when the HydraCAD template is selected, it goes straight to the drawing and command prompt, it doesn't ask for the user to set the scale factor

Upon calculating a file, the error message, "Failed to launch C:\HES\Hydratec for revit\programs\calcdiagnose.exe" pops up.

Was preceeded by these messages;

Plus this;  Number of Loops -1 and or Nodes with undesignated elevations

Selecting any button from the AutoCAD ribbon creates the fatal error.  Typing or using a toolbar does not create the error. 

AutoCAD Error Aborting

FATAL ERROR: Unhandled e0434352h Exception at 6C6CCF19h

Sometimes followed by;

The program is missing Tool Palettes and Ribbons.
The drawing may briefly open and then crash.

Background changes to gray and navigating drawing becomes sluggish after using the Newforma Konekt add in.

I can't find the 'Sentinel Product Key' for my Gemalto entitlement. 

When connecting a hard pipe armover to a flexible sprinkler connection (FSC), the flex hose doesn't continue straight, instead it immediately turns 90° before curving back and down to the sprinkler head.

Even with setting the connection to OVER-DOWN

When selecting a vertical pipe/riser nipple hydrapipe, the PROPERTIES window shows "no selection" instead of "hydrapipe"

You may notice that you cannot use the 'change length' command (CL) or cannot rotate riser nipple (RRT)

Revit could not complete the external command... Object Reference not set to an instance of an object.

Initialization Failed... Could not find part of the path