= Login fails with error message with HRESULT: 0x80131515
== Symptom
When starting {{{CDCplus.exe}}}, the
system shows the error message: 
> Could not load file or assembly '<filename>' or one of its dependencies. Operation is not supported.\\
> (Exception from HRESULT: 0x80131515)"

== Background
Windows mistrusts some libraries that are copied from external sources into system directories like {{{c:\Program Files}}}, marks them as insecure and blocks execution. This can happen on some systems, depending on the individual security policy situation. The block can be removed manually.

== Solution
* Navigate to the progam directory of {{{CDCplus.exe}}} and find the DLL named in the error message.
* Right-click the DLL and select "Properties".
* On the tab "General" under "Security", there is the entry:
> The file came from another computer and might be blocked to help protect this computer.
* Click the button "Unblock".