Site Thumbnails not working

Thumbnails no longer appear to be working.

For one of my bookmarks, the thumbnail image is
http://ma.gnolia.com/bookmarks/grazuz...

which gets redirected to
http://images.thmbnl.com/snapshots/20...

which then fails returning the following XML

<?xml version="1.0" encoding="UTF-8"?>
<error>
AccessDenied
<message>Request has expired</message>
<servertime>2008-05-14T10:57:03Z</servertime>
<expires>2008-05-14T10:56:59Z</expires>
<requestid>98E2F50630956C31</requestid>
<hostid>LikDbT8yLQTUheRpfmQ2XDV9F7G+/YR6WJGZYS4upRwx3y3mNbPxRN3xLv2/qoDd</hostid>
</error>

This appears to be happening with all of the site thumbnails. Everything was working fine yesterday.