this smells like a user permission error you will have to set file permissions to your files. can you do this? if no i can help
open "my computer",Tools,Folder Options,View,Uncheck "simple file sharing"
now on folder options you have a new tab security,open it,then remove all numeric(lost id) users, and add "everyone" or "administrators". that's it try to uncheck read only now.
enable simple file sharing again