Mark,
I don't restart my server through the Admin pages as I have always ssh access. However, your problem might be a premission issue. As the daemontools documentation states svc runs only with the permissions of the user and its primary group. All auxiliary groups of the user are ignored.
This can have unexpected side effects such as being able to execute the run file from the command line w/o errors but not when using svc. Make sure that root:root has read access to your config.tcl configuration file and the file with the addresses and ports nsd should listen to.
If root:root can't read the address configuration file then nsd won't prebind any addresses and thus fail to listen to ports http and https. There is not error message in the log when nsd can't read the address configuration file. There simply isn't the usual prebind message.
I hope this helps.
/Bart
