Lighttpd not cleanly restarting (address already in use)
It sounds like your "stop" script isn't actually stopping the server cleanly.
Can you post your /etc/init.d/lighttpd file?
Ok, sometime, when you install php5-mysql or php5-gd, it install automaticly apache2 (cause of the package dependence of Debian)
Try a top to see if apache isn't launch.
If it is installed : try a "apt-get remove apache2*"
It should be ok after
(Sorry for my bad english)