1. Close the QSAR Toolbox

2. Locate the .plugin.config file containing the profiler xml 

3. Back it up

4. Open it with a text editor (e.g. Notepad)

5. Replace all the occurrences of "<Family>Unknown</Family>" with "<Family>M</Family>"

6. Save it

7. Start the QSAR Toolbox and verify that you can now open the corrected scheme.