Ok, thanks a lot for your help.. checked the backup option and that was th eproblem... just fixed that.. will see a way to do it offsite (offmachine) via ftp...
And where is your backup space?? i have the same problem with several domains.. but cannot find where is this space being used..
I am getting into the ssh panel and checking directly with
du -h
but not even close to what plesk says it's using..