I'm having a weird problem with Windows Media Sharing on Windows 7 ..

I have the following hardware in my network:

PC 1 ---> My main PC ---> runs Windows 7 Ultimate x64 PC 2 ---> My backup PC ---> runs Windows 7 Ultimate x32 PS3

PC 1 is my main PC which has all my data/media on it .. PC 2 is a backup PC I have, but I use it like once in 2 months .. It has nothing installed on it apart from some very very basic software ...

Problem is, my PS3 always sees the media sharing service coming from PC 2, but it never sees the media sharing service coming from PC 1 initially .. Both PC 1 and PC 2 have the same media sharing configuration (All everything on all devices on all networks) ... But when I restart both PCs, the PS3 will only detect PC 2's media sharing service, not PC1 ....

However here's the twist .. When PC 1 is restarted, and if I view my 'Network' on PC 2, I do see PC 1's Media Sharing Service, and I'm able to play from it too on PC 2 ..

To get my PS3 to also see PC 1's media sharing service, I have to do either of the following 2 things:

1) Play something from PC 1's media sharing service on PC 2 ... The PS3 will then magically also detect PC 1's media sharing service .. 2) Go into the Services area on PC 1 and restart the 'Windows Media Player Network Sharing Service' ... After this, the PS3 also instantly starts to see PC 1's media sharing service ..

Since my PS3 is like a month old and is properly detecting PC 1's media sharing service, I think the problem is somewhere in the configuration of PC 1's media sharing service ...

Also, on PC 1 I have Norton Internet Security 2012 installed, but I've disabled it completely, and have also disabled Windows Firewall (from PC 1 only) ..

Can someone shed some light onto this ?