Unfortunately this problem hasn't occurred again since and I don't know how long it will take or what will trigger the problem to occur again. Interestingly, googling the problem did lead me to an IRC log briefly mentioning the same problem: http://irclogs.ubuntu.com/2005/12/26/%23kubuntu.txt
** Changed in: ubuntu Status: Incomplete => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/685790 Title: some program spewing "Command> Invalid command." to ~/.xsession-errors -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs