Temporary Issue - Networked PCs can't 'see' each other

[amp88]

Hi, everybody. I'm having an issue here and really struggling trying to diagnose and solve it. I'd appreciate any help you could give me.

Background on the situation:
There are 3 PCs in my home network.
PC1 - My gaming and general usage machine. OS: Vista Home Premium 32 bit, NIC: Intel Pro 1000/PT. Local IP: 192.168.1.3.
PC2 - My home server. OS: XP Pro SP2 x64. NIC: Intel Pro 1000/PT. Local IP: 192.168.1.2
The machines are on the same subnet (255.255.255.0) and same Windows workgroup. They have been happily playing along with each other for months and I have made no changes to their configuration lately. Each of the machines runs ESET Smart Security AV/Firewall.

The machines are connected with Cat6 to my gigabit switch (D-Link DGS-1008D, 8 port gigabit). The switch is connected with Cat5 to my ADSL router (US Robotics 9107).

The problem:
Yesterday afternoon I was using PC1 to listen to mp3s from a network share on PC2 and I also had a VNC session active from PC1 to PC2 (PC1 VNC client, PC2 VNC server). The mp3 stopped playing abruptly and the VNC session was unresponsive.
So, thinking there was a temporary glitch or something I ended the VNC session and tried to begin another one but I couldn't connect. I tried pinging PC2 from PC1 but got no response. I went to PC2 and tried pinging PC1 from it and there was no response. However, I COULD ping Google successfully from PC1 and PC2 separately.
After about 10 minutes of me scratching my head uselessly I tried pinging PC2 from PC1 again and it worked. VNC worked again and I could play the networked mp3s again.
This was the first time I've ever has this issue so I looked into the Event Viewer on PC1 and PC2 to see if there was anything of interest. There was nothing on PC1 but PC2 had an interesting entry in the "System" log:

Error: MrxSmb 8003

The master browser has received a server announcement from the computer GUS-PC that believes that it is the master browser for the domain on transport NetBT_Tcpip_{<String removed>}. The master browser is stopping or an election is being forced.

About 2 hours later the same thing happened (same symptoms, same self-solving nature). I looked at the event viewer again and PC2 had a new entry in "System":

Error: Service Control Manager 7006

The ScRegSetValueExW call failed for Type with the following error:
Access is denied.

I rebooted each machine and had no more problems last night. I had no more problems this morning but about 15 minutes ago the same thing happened again. Now there's an entry in PC1's event viewer:

bowser 8003

The master browser has received a server announcement from the computer GUS-SERVER that believes that it is the master browser for the domain on transport NetBT_Tcpip_{<String removed>. The master browser is stopping or an election is being forced.

I'm at a loss to understand exactly what is happening and why.

Any help or advice would be greatly appreciated. If you need any more details I will try to provide them. Thanks.

 

[Electrofreak]

I found some interesting information here.

 

[amp88]

I found some interesting information here.

Thanks for the reply. As the article suggested I looked for the "Computer Broswer" service in Administrative Tools -> Services. Both PC1 and PC2 had this service started, so I have disabled it on PC2 and will see if it stops the problems from arising.

 

[amp88]

After doing the above the problem hasn't re-occured yet, so it looks as though that fixed it. Still no closer to understanding why it happened after months of perfect operation though.