Listen to your upstairs neighbour! Provide more details!
Anyway, I'm guessing you want to rename or delete a file/folder and you get that error.
Maybe your file names/folder names contain characters from the extended character set...
1.Try renaming/deleting (depends on what you want) the files/folders from safe mode (f8 key on startup)
2.You can try renaming/deleting the files/folders via command prompt.
(if you don't know how to use cmd I'll provide more details)