except for .git, .gitignore and readme.md. Don't know if this is normal but I noticed that all the directory have the dates corresponding to when the error started to appear (instead of the installation date). Infact the plugins directory has the date correspondig to installation date (16 Dec.). But inside "plugins" all the sub-directory has the date of 21 Feb.
Edit: Nevermind...as I remember probably I ran the updater to try to fix the problem.
EDIT 2: It's VERY VERY STRANGE but I decided to reboot rtorrent.....and now all is working!!! I really don't know what happened