didnt get any response from the plugin forum, i think i might as well post this here.
if the directory name on server contains colon (:) or any other characters that are not allowed for directory name in windows, when you try to open/download a file in notepad++, FTP_synchronize gives an error "Unable to create directory for file ...". FTP_synchronize might need to replace illegal characters with something else when creating temp directories in windows.
and another small thing, just a little bit more intuitive, when the folder is empty the plus(expand) icon shouldnt be displayed.
Thanks for the good job on this plugin :)
I was receiving the same error ("Unable to create directory for file C") when trying to download files from the FTP sync to edit. It seems to be working properly now after selecting "Use nondefault cache location if none provided by profile" and choosing a directory under my user directory in Vista (e.g., C:\Users\Tim\Web). This setting is found under the General tab by clicking the cog in the FTP sync window. Hope this helps.