Earlier this week, during a business trip to Frankfurt, I connected my laptop to the hotel broadband. Today, I reconnected it to my home LAN and was disconcerted to see that it would no longer recognise the other PCs on the LAN. After tearing my hair out (not a good idea, given my tonsorially-challenged circumstances) for an hour, re-setting the router, re-allocating IP addresses, etc without success, I stumbled on the fact that the network name had been reset on the laptop - back to the XP default of 'MS_HOME'. Changing this to what it was before my hotel visit has fixed things.
I am a regular user of hotel and airport broadband and wireless hotspots and have never encountered this problem before. Thank goodness I found and fixed it before I tried an online flying session - I would have been screaming blue murder.
All's well that ends well, I suppose. Just thought my experience might be of use to someone else.