I tried it on another website (www.jbscomputers.nl/gallery) and that works fine. What's wrong? I don't think it's a PHP problem because joomla works fine.
Maybe this error from the php error log will help?
[Sat May 12 11:42:29 2007] [error] [client 62.195.201.5] File does not exist: /home/vhosts/tvderaam.nl/httpdocs/gallery/<
[Sat May 12 11:42:29 2007] [error] [client 62.195.201.5] File does not exist: /home/vhosts/tvderaam.nl/httpdocs/gallery/undefinedgetconfig.undefined