[thelist] crazy inexplicable overlay in Firefox

[sbeam]

Hi all ~

we have a report of a strange issue with this site in Firefox 3.0.8+ on OSX - 
seems to be showing a grey semi-transparent overlay that blocks interaction, 
but only extends partially down the page (below the viewport, but not to the 
end of the page)  http://tr.im/kcDa

here is a screenshot of it -
http://dev1.onsetcorps.net/ss12.jpg

Testing on other systems with same browser and OS shows no problem. He has no 
unusual plugins that I know of... and there is definitely nothing used 
anywhere in the site that creates any kind of overlay.

Actually here is one report of a similar thing that self-resolved -
http://groups.google.com/group/blogger-help-troubleshoot/browse_thread/thread/52c2f283f3ae6a2a

but this one doesn't. Anyone else see anything like this, on any other site?

Also, is there some sort of law written in stone tablets that says "At launch, 
your site will look perfect in every browser, except for the exact one your 
client happens to be using"?

thanks much
Sam