Home Network Set But Windows 7 Says Can't Join Homegroup, No Home Network

5 month old Dell XPS 8500 Win 7 64 bit Pro as main computer connected by Wired Adapter, Upgraded Gateway 5632E also running Win 7 64 bit pro as second connected by Wireless. Both running Kapersky successfully. no network problems for 5 mo.

Both were successfully linked using homegroup. Had to take Gateway to a remote location to do a business demo. While there had to link to a local public WiFi. While connecting made mistake and left homegroup.

When Gateway returned to homebase a few days later it was fine, had no problems finding wireless but could not see or rejoin Dell machine homegroup. It would let me set up a new homegroup.

Went to Dell box and found 1) homegroup no longer existed, 2) router and network and wireless printing no longer found - Red X on the taskbar) even though internet was still working fine.

Took nearly a week of trying differernt fixes, on adapter- off adapter- different adapter reboot network, router, even updated router firmware (Yes I went through every ipconfig reset, renew, redecorate etc. I've used netsh functions to try to get evrything to reset. Changes services.msc settings per other posts. Finally in desperation, deleted every sub key in the registry related to network locational awareness and got the Dell to find the network, let me set it up as a "home" network and then even see the invitation to join the Gateway's homegroup.

Then I hit a wall- when I try to join- Win 7 says I can't join the homegroup because the network is not a "home network". Of course troubleshooting is useless and goes into an endless loop. Have searched in desperation for any way to make Win 7 return to a clean slate so it can sense that it really is on a home network without success. Applied the fix-it and hotpatch for when Win 7 gets stuck in public mode. No joy. Deleted the hide wizard subkey as suggested elsewhere. No Joy. Gut feeling says problem must lie in the NLA or peer networking somewhere but where?

Does anyone know of a method or set of steps (short of a clean reinstall of Win 7) to completely clear every thing the OS knows about my network and force it to acknowlege my network is a home network? Is there a registry hack that will clear the problem?

I know I could abandon the homegroup and do conventional file/print share but I am concerned that using that solution won't last as whatever is screwing up the homegroup could eventually screw regular sharing and then I'm back to reformating/reinstalling. I'm just about ready to join the Apple folks so I never have to work on Windows again.