Looks like a hardware problem (?) after all. I reconnected the sata cables and everything went back to normal! Solution from: http://ubuntuforums.org/showthread.php?p=9994345
** Changed in: coreutils (Ubuntu) Status: New => Invalid -- [md5sum] checksum of dvd images OK, but system becomes unresponsive (high memory usage) https://bugs.launchpad.net/bugs/664066 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs