Machine Name "Progressively" Lost on Network

[alov1258]

I have an ongoing issue which has been getting worse over time and I cannot get to the bottom of it. I have one machine on my home network which "progressively" disappears from the network. A reboot always fixes the problem, and it is only this machine. The machine in question is my main file server and a HTPC, so reboots are not always convenient. The machine is running W7 Professional. The first symptom of the problem is the machine cannot be found by WDTV boxes and my Sonos ZonePlayer, but media servers (Tversity, Windows) still work fine, and so does Windows Networking and Remote Desktop (RDP). The next stage, RDP cannot find the machine by name (machine cannot be found in NetBIOS error), but works if I use the IP address. Eventually, the HTPC can no longer be seen on the network by the other Windows machines (shares are lost), but it can see itself and the the rest of the network. At this stage, a reboot of the HTPC is required to get it back and working which may work for several hours or days. A bit about my network.

Router is Billion 7404 VGPX connected to the internet. Firewall turned off. This is connected to an HP Procurve 8 port switch into which the PC's and HTPC are connected. I have two other PC's on the network, all running W7 Pro. Also connected to the network are a Brother 2140W printer, a Sonos ZoneBridge and ZonePlayer, and an Asus RT-n12 access point. I use Norton Internet Security 2011 for antivirus and firewall.

The HTPC runs a Gigabyte GA-MA790X-UD4P motherboard and I am using the NIC on the motherboard for network access.

Any ideas or suggestions on how to track this one down and fix will be appreciated.

Thanks