[DiapDealer]

Actually, loading the Sigil exe in Dependency Walker when Diskeeper is installed should be enough. If Diskeeper being installed keeps Sigil from launching altogether, then Dependency Walker should prominently display a big, fat red error rather quickly.

EDIT: it's as easy as File->Open, and browse to the Sigil exe. Profiling is a little more in-depth, but since Sigil won't launch, that's not really an option anyway.