The problems discussed in http://noticeboard.ru.ac.za/post.5532683 continue -- about fifteen minutes ago, both of the University's proxy servers stopped responding. This will have resulted in an apparent Internet outage, as most websites would have been inaccessible. One of the two is now responding, and the other is in the process of rebooting.
Unfortunately the cause of this is not understood. It would seem that it is not the network cards, as previously thought. Until it is, it is likely to recur.