Network discovery turns off after reboot (sometimes).

I have a home network with a Belkin wirless router / ADSL modem which three client machines connect to wirelessly (kid's, wife's and my work PC). In addition to my main work PC I have a secondary PC I also use for work that I have set up so that it is connected to the wireless network via my main PC.

So the setup is:

Router --> Air waves --> Kid's XP machine, Wif'e's Vista machine.
Router ---> Air waves ---> Main Vista (32-bit) desktop --> Wired connection (10/100 switch) --> Secondary Vista (64-bit) desktop.

The way I have the connection configured on my 32-bit Vista desktop setup is:

Wireless Network Connection - static IP ( /
Local Area Connection - static IP ( /

Then I have the above two connections bridged using a Network bridge with IP All machines on the wireless network see the main 32-it Vista machine as, as I want.

Everything works great under this set up. I can ping each and every machine from every location on the network, internet access works, file sharing works (and I get the wired speeds between my two local machines) and life is generally grand.

One problem, however, and it's just an annoyance, but maybe one for which there is an easy solution, and that is that the 64-bit Vista machine seems to perodically turn off network discovery. I use a keyboard/mouse sharing program and usually log in to the 64-bit machine with my common keyboard/mouse, but every now and then I can't do that because the connection fails. When that happens I have to log into the 64-bit machine (plug in a keyboard and mouse) and RE-enable network discovery. After that everything is great again, until a couple of weeks later and about 5 or 6 restarts it happens again.

Does anyone know why the 64-bit machine keeps turning off network discovery periodically? The only additional piece of information I have, seeing this just happened is that under the Network and Sharing Center on the 64-bit machine, the local network is shown as "Unidentified network" and when I select "Merge or delete network locations" it shows the previous network location(s) as "Not in use". So it seems to be that it forgets that it already knows about the network... Frustrating but since it's not that often that it happens and not that often that I reboot, I've just been living with it, but a solution would be nice!

Any suggestions?