[Chameleon] tiff hang

[Ken-ichi]

Hi list.  A while ago I posted an issue I'd been having with rendering 
TIFFs in Chameleon 
(http://lists.maptools.org/pipermail/chameleon/2004-August/thread.html#1245), 
but I never really resolved it.  Essentially, whenever I zoom in on a 
GeoTIFF so that the TIFF fills the whole map, Chameleon hangs and never 
displays the map image (I just get the spinner icon indefinitely and 
then a broken image icon behind it.  Try zooming in on the DRG (Test 
Raster) at

http://fisher.cnr.berkeley.edu/vtm/data/mapbrowse/

to see what I'm talking about.  I'm fairly sure this is a Chameleon 
issue, most likely with drawmap.php, because this mapfile renders just 
fine via the CGI, and with a rudimentary phpMapScript app like this one:

http://fisher.cnr.berkeley.edu/~kueda/mapscript_browse.phtml

The DRG is a 16M GeoTIFF from the California Spatial Information 
Library, so I don't think it's to blame.  You can check out my php and 
MapScript config at

http://fisher.cnr.berkeley.edu/~kueda/phpinfo_mapscript.phtml

I'm running MapServer 4.4.0, GDAL 1.2.5, and PHP 4.3.9.  Can anyone 
think of a reason this could be happening, or recommend a way to 
troubleshoot drawmap.php?

-Ken-ichi