Hi Ouning
Did you have any more luck with the last log file I sent (from when Safari was showing this problem)?
Since then, Firefox has stopped, started and stopped working again, unfortunately I haven't had time to reinstall the logging software a third time, but it does seem to form a pattern: if you don't use firefox for a couple of days it will work. When you go back to it the following day, you'll find it has stopped working.
Jeremy
