I also have the problem of unidentified network, public and am unable to access the internet.
Is this the place to post my problem by joining in to this discussion and to seek help (I've never posted anywhere in the world before)?
The PC is my main work PC with my files and e-mail. It is one of several towers and laptops in the house, it is Windows 7, was on the internet for most of its 2 year life, though this problem happened twice before. Last time I did a system restore, which failed, but the internet did come back anyway, by doing the restore. That was Aug 2010.
All the other PC's belonging to family members, myself in other rooms, or visitors all just go on, wired or wireless.
This failed 5 days ago and is driving me crazy!! The Windows gadgets / RSS desktop feed seem to see the internet and I can fx it by doing a diagnostic on the NIC (which has the latest driver) or by uninstalling and re-installing the NIC - but it goes absent again, always, within approx 60 seconds. I changes from a named Home network with Homegroup, to an unidentified betwork with a public profile. Then it says that the Internet is still available, but I cannot browse or use e-mail.
I have tried ans succeeded, a few seconds at a time because of time-limited connection, to obtain the latest Intel 82566-DM2 drivers, the diagnostics say no valid gateway, they auto repair that, giving me another 60secsw or so.
I have tried setting the IP and default gateway by hand with Google DNS servers, no connection. I do not have Bonjour. I replaced my antivirus and firewall and spyware protection.
Historically there are 2 broadband sources here, one cable and one phone line, with two wireless routers and mainsnetworking and a switch going to NAS media drives. The idea was to have reliability, especially as the downstairs router couldn't send wireless to the bottom of the garden building where my wife runs sports club admin. In fact, originally I didn't know if it would work with the 2 networks linked together via the switch going to the NAS drives. But for years and months all machines would use either broadband, though not all machines could reliably see the music library. It led to the interesting situation where one ogf the mains networking pair is on 192.168.1.x and the other one is on 10.0.0.x as these were the respective IP areas of the two broadbands.
But, from here, upstairs, this all just works - it has continued to work ever since I started this upstairs PC also about 2 years ago and it works now - I can see the broadband and the machine downstairs and its shares. But tthis upstairs PC doesn't have all the programs on that I have and need in my downstairs. To simplify things though, I did separate the 2 supplies from mingling at PC level a couple of days ago, including removing the wireless link from the main machine to the alternate broadband.
Earlier, three days ago I also tried simplifying everything. I switched off the broadband router the machine normally uses, I hard wired from the alternate supply i.e direct from the cable router to the main machine usong tens of metres of network cable, then switched off the cable modem and the PC and re-booted first the modem and then, 3 minutes later, the PC, so that it would negotiate the correct ip and dns and it worked. For about 60 seconds, before the Home neywork again became unidentified. Resetting and fiddling with the NIC gave the usual very brief connection.
I have checked other things. As soon as it fails, the network discovery service becomes switched off, though the 3 services that MS Windows Help (on board) says that are needed, do continue to run. The default gateway disappears. I can see no iterms in MSConfig or in Services or in the Programs list or as candidates for removal, that worry me.
All this an much more troubleshooting has happened over the past 5 days since it stopped connecting out of the blue, I may have mis-remembered bits but have done my best and am at my wits end to get my internet back on the main PC.
Thanks anone who can suggest the solution.