Intellectual Error messages

When automating PowerPoint you might get following error:

“COMException: Presentation (unknown member) : An error occurred while PowerPoint was saving the file.”

I have always been asking myself, how to find an optimal path in my brain able to lookup some solution for such errors. Because, the entropy of useful information of this message is nearby zero, it is mathematically almost impossible to solve it. Solving this is equal to finding of solution for some unknown problem.
But, empirically there is a way to narrow the problem. Just, don’t trust the message. Some COM/Office/Errors can mean anything, but not that what you see. :)

This message means, that you are trying to save the file (by using of Presentation.Save or Presentation.SaveCopyAs) to some directory which does not exists.