1) In Serum, Menu->Show Serum presets folder Go in to Skins folder - make sure there are no files there which don't belong. - make sure no skin folder names are too long (~30 chars is limit) 2) delete the Serum.cfg file [MAC OS] command-shift-G in Finder and type or paste the following line (including ~ mark): ~/Library/Preferences/ delete Serum.cfg file located there. [WINDOWS] %APPDATA%\Xfer\Serum delete Serum.cfg