Don't use the domain name with GET, use the path.

sockwrite checktv GET quickinfo.php?show= $+ %checktv $+ &exact=1 $+ $crlf

I also add the http auth stuff in this line.
Code:
sockwrite checktv GET quickinfo.php?show= $+ %checktv $+ &exact=1 $+ $crlf $+(HTTP/1.0,$crlf,User-Agent: WaTech,$crlf,Accept:) $+(*/*,$crlf,Host:) www.domain_name



None of my socket scripts have had any issues transitioning from XP to Vista.

If this doesn't fix it then I would verify the status of your connection during the different sock events.