I have various machines running Ubuntu from 10.04 to 12.10. All of them suffer from a problem which uses up all the HDD space on the file system drive until it is rebooted and all the space is back again. The GUI wont load (usually) one time I did get it to and ran disk analyser, which showed that the HDD still "had space left", yet at the same time I had the box popping up saying that File System was out of space. I did find once that there was a file xsession-errors, which was 700GB in size. I have put a fix in place for this, so now I dont know what is causing it. Any ideas please!? The only thing in common is they all run Virtualbox, however, I cant find any signs that Virtualbox is the cause.