Hey Phil, don't know if you've went this route but, my house is full of x10, but i do not use girder. I use homeseer. have you tried to use that program, it works great with all x10 modules. XL has a plugin that talks to HS. I have had no issues with that program. If you can do it, i highly recommend it. Bill and Jay put me on to this program.
If I remember,you need to update gireventlib.dll used for sending event to girder, try to get the one provided in girder 4 directory and put it in the xlobby dir
After some searching, I found a copy of Girder 3.2.9 and the right plugin for X-10 and it is working nicely now.
I will take a look at Homeseer to see what that offers. I like Girder (not because it is so well designed....) because it gives me Zoomplayer and X-10 in 1 app. I have tried to simplified the number of apps required to make my system do what I want.
Since I never could get the builtin video player to work and the built in "XL Services" does not support X-10 native (I did try Insteon a bit as well), I am forced down this route but it is working so I am not complaining.