I am a user and filter author and not a employee of FF INc...I would suggest to download the trial and see if you have the same thing..ie...clicking a filter and it tries to open in the editor....It could be that the click on your mouse (if you are using a mouse) could be set to close of a double click....Or the mouse could be getting wonky....Without details one must first eliminate the easy things to go wrong or possible things to go wrong first........
Read the quote in my post and that is what I compute by..
btw FF most likley cannot reproduce the error that you are having so they can only guess at what it might be....That is the number one rule to finding bugs in an application....Before you can fix a bug one must be able to reproduce the bug to see whats going on...
So here is something to try....Turn your double-click amount down in windows...So there is a delay between clicks....When a filter is double-clicked it will open up that filter in the editor....Since you are on the basic edition it will still try to open the filter in the editor but give you that box since you cannot edit in that edition......
Stupid things happen to computers for stupid reasons at stupid times!