I was unable to delete this in my folder - apparently it was corrupt and I didn't have permission (only two optiosn were Try Again or Cancel). Managed to delete the file through the game load menu itself. Reloaded another save, hit quicksave, and now its just got a corrupt message with "cannot load." I can't delete it through the game. I can't delete, move or rename it in the folder (again, apparently, I need permission, though this time it doesn't tell me its corrupt).
I now no longer have a functioning quicksave option AT ALL.
Fortunately, I save often and in multiple slots. Autosave is still working, too. This still does not excuse the fact that quicksave is compeltely broken for me.