I am running Debian testing.

I installed lighttpd and, among other things, enabled the fastcgi-php-fpm module. At this point lighttpd was functioning properly as expected.

Then I installed phpmyadmin and asked it to configure automatically for lighttpd. This caused lighttpd to be unable to start. I determined that this was due to the fact that the postinst script in the phpmyadmin package enables the lighttpd fastcgi-php module:
lighty-enable-mod phpmyadmin auth fastcgi fastcgi-php

My solution was to manually disable the fastcgi-php module, which allowed lighttpd to start again.

But I don't think that the phpmyadmin postinst should enable fastcgi-php when the fastcgi-php-fpm module is already enabled.

Let me know if I can provide any further information.

Thank you,
James Dietrich