On http://www.wikipedia.org/wiki/Feigenbaum_constant I see:
Warning: pack type H: not enough input, need 16, have 15 in /usr/local/apache/htdocs/w/OutputPage.php on line 72
The line is: $outputhash = unpack ("H32md5", $rpage->math_outputhash);
It's triggered by this tex fragment:
<math>\delta = 4.6692\cdots</math>
Inserting it into Wikipedia:Sandbox gives the same error there. On submit it becomes all-encompassing; on page view it just hides behind the regular text.
Adding a space to alter the input hash, or clearing it from the math table causes the next load (with render) to work fine; on reload, the error comes up.
Changing \delta to \alpha makes it play nice.
-- brion vibber (brion @ pobox.com)