Error message "unable to find file"

Can anyone help me with what to do with this error message?
 I recently began using Ecco on Windows 7. Works fine and I can open a file from the File --> Open menu with no problem.
 

 But if I double click on an .eco file to open it,  Ecco opens ok but doesn't load the file. Instead I get the error message "Unable fo find file"
 

 Sometimes this is followed with <text is unavailable>  or the actual file name that I wanted load as in <c:\filename.eco>
 

 Any help is much appreciated.