A month ago I set up a multisite install following instructions given here. It worked for a few weeks and I set up a number of sites within the network. I now find when logging in to the base site that the network admin option has disappeared - it used to be under My sites.
This is the second time this has happened to me. The first time I only had one site set up and blew it away. This time I have 8 and don't have the time to rebuild them all.