this exact thing is happening to me on my ws-2000, too, and it's been driving me crazy all day. i thought it was something in my network, and spent a lot of time trying different DNS and time servers. these changes didn't seem to have any real impact. like alanb i do seem to be getting updates through, but with longer intervals, but my icon is also disappearing.
anyway, thanks for posting, and thanks everyone for replying! it's very reassuring to know the problem is not on my end.