Also want to note I experience mIRC completely freezes for a few seconds when connecting to an IRC server for the first time, when "Ident server" is checked in the UPnP options.
When I then go to UPnP options and deselect "Ident server", it reports UPnP support is not available on my system. (I would except the check only to occur when checking one of the UPnP options). But anyway, UPnP is enabled on my system (Windows 7) and on my router.
And now, some minutes later, it doesn't give the error anymore, but still freezes for some seconds when connecting.