This error may occur if you try to open a Relux project by double-clicking.

This message will appear .


This error may also occur with other files from AutoCAD and Microsoft Office.

According to Microsoft, this is a so-called DDE error, basically a communication problem between the programs.

  If you first open Relux or the corresponding program and out the files, the error does not occur.

This error message does not appear when you select the corresponding file in the folder and select the  "Open"  option from the right mouse button.