I have trawled the various forums without success. The only firewall running is Windows Firewall and the problem persists even when this is disabled completely. I have all the recommended ports open regardless (both at router & WF level), I have tried stop/starting the various services as suggested elsewhere on the forum and emptying the DRM folder, none of which works.
Xbox support were useless, eventually stating that because my PC was cabled into the router and the xboxes were wireless, they would not work and everything either had to be wired or wireless but no mix "because the software is incompatible and can't form a bridge" which sounds like nonsense. The only other devices I have linked are an iMac running wirelessly along with a wireless printer.
I've even tried going back to just the old single xbox and that doesn't work either. I also can't get Windows Media Centre to set up - it fails after punching in the 8-digit code and reports "extender not found".
I recently came across a post elsewhere that suggested that the problem could be that the PC and the xbox are not on the same subnet. I use a Netgear WRN2000 router and proprietory modem (both provided by my ISP - Virgin) but when I click 'full map' on my network, I can see that the PC is connected via a virtual 'switch' to the router and then both xboxes hang directly off the router. Could this be the source of the issue and if so, how do I get around it? There is no opportunity to cable up the two xboxes which need to remain wireless and currently the PC does not have a wireless card so needs to remain wired if possible.
For the record, I'm running a Core i7, 6Gb machine with Vista Home Premium 64.
I'm so frustrated with this but here's the strange thing - I did at one point (randomly) get it working (no idea how) but about a week later it disappeared again and I have no idea why. If anyone could help me solve this one, I'd be extremely grateful.