2 things to try.

1I have Vista and it gets annoying sometimes when I try to move folders for some reason when I paste the folder at the bottom of the folder I want it to go in it sometimes goes into the lowest folder. So it's no longer in my interface folder instead it winds up in interface/zzzzzz folder.

2. Check your account/WTF folder under the saved variables or whatever for the SDM.lua. Whereever it saves the profile not the actual interface folder. Sometimes it reads that as already being installed when there is a saved profile. Delete this as well.

Extra: on a side note if anyone knows how to delete the created folders of Super duper macro that would be great. The addon allows you to create subfolders in game to save your macros and I have made a few toons which I deleted but their folder stays there.. Can't seem to find out where in the saved variable I can delete to get rid of that toon's folder. Wish they made a delete button for the folder.. Too bad they only made a delete button for the macro's themselves.