I'm guessing that the "nothing" that changed, was one or more Windows 7 updates.
What are the static IP addresses of the WLIPs? And what are the IP addresses of the Windows XP and the Windows 7 computers?
They are all on the same network, and are all publically addressable IP's too... gateway is .129 , WLIP's are .136 and .169 , the Win 7 box is .133
The WinXP box was disconnected from the rest of the network, and connected to the WLIP by switch that wasn't connected up to the rest of the network, just the WLIP's.
The WLIP that I was having the issues was then visible to WL updater, but not otherwise visible.
In response to Aardvark's
IF you put in the IP address of your IP logger do you get this , but for your logger. here is my IP logger that goes to my WL2.0
Not with the original WLIP which started this all off, however with my other WLIP, it does.