I do not get this message. Are you using a different IP address? You could also try reloading the graphics to hopefully get something that is at least readable.
Thanks both. Not aware of any changed settings but I'll take another hard look later when I get back on my PC. It's interesting to note that I'm answering this on my iPad without the problem.
Edit: Now back on my PC - and the problem has gone. No changes on my part. So just one of those mysterious glitches...