Thanks Ed. User name doesn't show in either Firefox or Camino browsers (on a PPC Mac). The text 'welcome back snags' is actually there (as a clickable link to the home page?) but is the same red colour as the panel rather than white out. Anyway, it doesn't seem to be effecting anything else so I'll forget it... will just have to be careful about who's account I'm posting from.
I've never had this but it's easy to replicate the problem with three clicks- just right click on that bit of the screen, select source and then delete the line of programming language. Maybe you clicked on something by accident or something isn't working on your laptop. If you log out, clear your cache completely and then log back in do you get the "welcome back snags" message now?