During the install of HydraKEY, this error message pops up.  Of note, if not paying close attention, it looks like it installed properly due to the 'Completed' message at the top and the FINISHED button at the end, but if you read closely, you'll see this information.

InstallShield Wizard Completed

The wizard was interrupted before HydraKey could be completely installed.  

Your system has not been modified.  To complete installation at another time, please run setup again.

Click Finish to exit the wizard

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

When trying to create a new Info Sheet, you're greeted with the error; 

Error during load of .INF data, mismatched file versus form

When viewing the final calc printout, the info sheet shows the line,

text1(35) - invisible

While trying to calculate a job, an error message pops up saying the following

"Error in Calc Engine"

Error in processing data of calculation;

-If this is a grid, uncheck 'Autopeak' and try again or,

-Confirm the node you set as the calculation source node exists in your input or,

- Check for incorrect values in your densities, areas or pressures

During running your calculation, and after receiving the summary regarding your safety margin, you get a similar error.

You'll then likely get these errors, up to 3 times.

Be aware these windows may be BEHIND the calc window, so move the calc window out of the way if it looks like it has crashed or is hung; 

Trying run a calculation as stand-alone, or via AutoCAD/AutoCALC or Revit/AutoCALC, you get this error message;

Run-time error 339:  Runtime error 339  Runtime 339
Component 'MSCOMCTL.OCX' or one of its dependencies not correctly registered: a file is missing or invalid

It's likely a job without a pump works, but one with a pump crashes
 

When trying to print final, the dialog box HydraVIEW, Run-time error 9, Subscript out of range

When trying to edit the company information by going to the menu [Utilities|Alter Company Information], you get the error saying, "Error trying to edit company information", Please get a copy of {\...\Company1.dat} onto this computer".

When attempting to print a final calc, nothing happens and HydraVIEW doesn't open.

You can test this by trying to manually open HydraVIEW.  Go to the Windows START button, scroll down to the letter H, select Hydratec v50 Software, then select HydraVIEW.  It should open to a blank job, but if nothing happens, see below for the possible solution.

You can also manually attempt to navigate to this folder, then double-click HydraVIEW.EXE;

"C:\HES\Common\Ver50\HydraVIEW.EXE"