The good news is that White queens are back today!

Its working ok for me in Firefox. This doesn't explain the problem but I think the link to you posted below to the white queen piece is wrong:
http://chesstempo.com/images/merida/whitequeen46.pgnNote, the extension, that should be png not pgn.
see if this works:
http://chesstempo.com/images/merida/whitequeen46.pngDid you type the url or cut and paste it from the UI? Could you please double check to verify if the .pgn is a typo or not? (the only 404 I have in the logs is for the .pgn file and comes from the same IP address you posted from).
You are most likely right. I couldn't copy the url from the status bar, so I had to type it in, making that part of my bug report bogus.

If its a typo then it still doesn't address why the white queen doesn't load for you. It is possible that either your browser cache or your ISP's proxy had trouble accessing chesstempo at some point and is refusing to check for the image again. You might try forcing a reload on your browser (and maybe also clearing your browser cache), to see if that helps.
Another possibility is that some of the bytes in the queen image are creating a false positive in your anti-virus software. If you are feeling brave you could temporarily disable any anti-virus software to see if things work with it off.
Those are two good theories. I think that we can discard the anti-virus one, since I can now see the White queens again, and my last anti-virus update came from 2/15. The proxy theory seems much more plausible at this point. I indeed connect through a proxy. I should have turned the proxy off and double-checked, but I wasn't thinking clearly yesterday. Anyhow, sorry for the trouble, as this is most likely an issue on my side.