Help! WDTV *Sometimes* Cannot see my network shared folders?

Guys this is driving me mad, I’m really hoping someone can help me.

I have a wireless network at home - my PC has XP Home and has a number of sharted folders. I also have a mac in my bedroom whioch I stream movies etc over the network all the time, works flawlessly.

I got a WDTV and it worked perfectly for the first week, found my shared folders on the network and I played all my movies and music on my tv no problem. The WDTV is conencted to the network via RJ45.

One day I went into network shared, but clicking OK did nothing. I actually have my betwork bridged with my neighbour and his shared folders show up, but not my PC. I tried it the next day and it was back, working fine. However sinbce them 4/5 times I try it, I cannot see my PC shared folders. 

I have tried resetting all the settings, clearing the saved passwords (there is no password on the network) - and sometimes it works but more often not. 

Can anyone tell me what might be causing this problem and how I can fix it? It’s driving me mad that it is not working as it should all the time…