Al,
The script uses two cache files
OSEIiod.jpg
OSEIiod-cache.jpg
Those files are on your site, but seem to have been last updated 'Last-Modified: Tue, 23 Dec 2008 14:18:10 GMT'
I suspect those files aren't writable by PHP .. try changing the permissions on both files to 666 so that PHP can write them.
It would be good to check out the other cache files used by your website to make sure they are writable also
forecast.txt
uv-forecast.txt
Best regards,
Ken