i checked the file paths and they are correct based on what you stated the "~" means.  i still get a security error. below is my paths.  in IIS the DotNetNuke folder is my root app folder.  so the filespath should be correct by default install, the folder path i modified and copied the sample folder over.

 

    FilesPath  = "~/DesktopModules/dotnetgallery/DotNetGallery_Files"
    FolderPath = "~/DesktopModules/samplefolder"

 
any other suggestions?