Please choose one way to connect the master with the client: either nsunix _or_ nssock. The recommended way would be nsunix, unless you have specific reasons to use nssock. Don't load the nssock module on the client servers at all, e.g. remove it from the ns/server/ottm_cserver/modules section, that should eliminate one possible cause for confusion. On the master, only load nssock, not nsunix. Of course you can later activate nssock on the client again, if you have the need to bypass the master by specifying a specific port number.
The config snippets you posted look ok - you just might want to add a mapping for each domain name with port 80 explicitely listed, like this to accomodate certain client programs (I think wget for example):
ns_param "ottawamax.ca:80" "unix://ottawamax.nsunix"
Also did you look in the master's log file? According to your server namings it's propably called server.vhr-master.log. Search it for occurences of the word nsunix and possible "connection failed" messages near it.