Just to say:
Is working fine here with lighttpd and php-cgi5:
PHP 5.2.3-1+b1
lighttpd-1.4.18 (ssl)
There were indeed a few things to enable in php.ini though (url open through file access must be enabled) and the lighttpd server must have WRITE access in the directories concerned as it writes the chart to the basedir of the script.
Definitly look at the php.log file. It shows what is going wrong.
The only slight problem is that its slow on a slug, but I dont think that can be helped:
This page took 4.366378 seconds to load. (summary)
This page took 15.977312 seconds to load. (Artist)
This page took 14.669310 seconds to load. (Genre)
This page took 13.459053 seconds to load. (Albums)
This page took 1.608553 seconds to load. (Tracks)
This page took 2.781499 seconds to load. (Decades)
This page took 8.203721 seconds to load. (Last added)
Refresh charts –> ages, ca. 40 secs.