My Network Places empty, but networking seems fine

So, I'm having a bit of an issue that appears to be affecting all the computers  on my home network (XP pro x64 SP2, XP Home SP2, XP Home SP3, XP Pro SP3). Everything has been running fine for the past year or so that I've been in the home and then all of a sudden, within the past few days, this issue hit. I cannot connect  directly to any of the shared folders on my network via the My Network Places folder. There are no longer any shared folders showing up there. I try to manually search the network for shared folders by opening Entire Network->Microsoft  Windows Network (slower than normal here to find my workgroup, WORKGROUP)-> WORKGROUP. Once I try to open my workgroup, it waits for awhile and then I get the error: "Workgroup is not accessible. You might not have permission to use this network resource. Contact the administrator of this server  to find out if you have access permissions. The list of servers  for this workgroup is not currently available. ". Note that all my PCs are in this workgroup.  Internet  is working fine on all computers, and I can access any shared drives I've got mapped (or enter the network path into Run and open it up) and can ping other PCs  on the network, so I don't think there's any issue with network adapters, and it's happening on 4 separate computers with different network adapters so it's hard to believe they all got corrupted somehow... The only thing I can think of is that I have automatic updates enabled and perhaps MS released an update that caused this issue.  Has anyone seen/heard anything like this? Any ideas what could be causing this or how to resolve this? Any steps to try? This isn't a critical issue, as I mentioned I can still access shared folders, just need to map them or something, it's just frustrating that something which used to work find just stopped, all of a sudden, with no good reason, and everything I can think of that's related still seems to be fine...  Thanks in advance!