For those who use some other character map other than standart US ASCII, there sometimes happen some files, who has some nasty characters in its name, which appears in your Windows Explorer but
when you try to delete it, it says system cannot find the file.
In order to delete -or rename, whichever you like- that nasty file,
you can use any ftp client with a visual GUI, like WS-FTP or so.
In the ftp client's browser window, go to the folder containing that file and edit/delete it in there.