Changed broadband providers today at the shop. The most modern PC is the only one with Windows 7 and it is the now only one that now refuses to see other PCs on our little network. I do a lot of file sharing between 3 different PCs - one of them has XP and the other is just a glorified print spooler running 98. The others all see each other as though nothing has changed, but the Win7 machine thinks it is alone on an island. It still accesses internet fine but won't see shared resources on the old PCs.
When this 'puter was new a couple months ago, I had a similar problem, but I can't remember what I did. I kinda remember there being a "trust all PCs on this side of the router" check box but I can find no such thing now. I've banged on all the Troubleshooters but they are mostly useless. From what I can find, all the right stuff is enabled. I can ping the other PCs successfully and send files to the engraving machine controller but no shared folders!