Network Issue

[#1]

Hey all,
Apologies if this isn't the appropriate sub-forum, haven't a clue what is causing it so I took a guess that this was the best place to post it.
Just built my SO a new PC and since adding it to the network I've had the same issue everytime I turn my PC on (the only other PC in the network). Basically everytime I turn my PC on it states that I have no network access and no internet access (warning triangle displays on the network connection), the only way I can resolve this is to unplug the network cable from her PC and then once mine gets network access, plug it back in. Once mine has network access then it works perfectly until I boot her PC and then shut it down, once I shut her PC down the same issue occurs until I un-plug her PC and then the cycle repeats.
My network setup is as follows:
Router (Linksys WAG320N) connected to the phone socket downstairs, which is then hardwired (1gbps) to a network socket connected to network socket upstairs, a 5 port (1gbps) ethernet unmanaged hub is then connected to the upstairs socket and the two PCs are connected into this hub.
I have tried the usual network related troubleshooting methods, I've used static IPs, dynamic IPs, plugged the network cables into different ports on the hub, checked that we are both using seperate IPs, and it all looks ok. I've even switched routers (from Linksys WAG160N to WAG320N), and the same issue persists.
I'm wondering if it is some feature of my SO's PC that it keeps an active network connection when it is off that allows it to search for magic packets, which is causing my PC to fail to connect. I've been through the bios of her MB and have been unable to find any setting that sounds like it could be causing the problem and I have made sure that we both have the latest drivers for the network cards via Windows 8 Update. Incase it is relevant, her new MB is http://uk.gigabyte.com/products/product-page.aspx?pid=4441#ov and my MB is http://uk.msi.com/product/mb/P67A-GD53.html and we are both using the onboard network adapter.
Any advice you guys could give would be greatly appreciated.
Dave

[#2]

It certainly sounds like a hub - although nobody sells hubs these days. 
Do hubs work with DHCP???
I suspect you need a switch (these can be found new quite cheaply).
Works for me:-
Router -> ethernet over power cables -> 5 port switch -> 2 devices. 

[#3]

Apologies, I mean't a switch, my bad. It's this one:
http://www.netgear.com/service-provider/products/switches/unmanaged-desktop-switches/gs105.aspx

[#4]

Does it still fail if you leave the ethernet cable plugged into the SO machine - but you disconnect it from the mains?

[#5]

Apologies I've had a chance to play with it further and I got some information wrong in my original post, if I unplug her PC from either the network or the mains then I get a network connection no problem, the moment I plug hers back in I lose network connection. If I turn her PC on and then shut it down then I keep my network connection until I restart my PC/cycle the network adapter.
Dave.

[#6]

Have you tried swapping the cables in the hope that the problem follows the cables?

[#7]

Sounds to me like you may have a cable issue - eg a crossover cable where there should be a straight patch cable. It's also possible that your router / switch isn't auto sensing / switching for cross over cables and thus can't tell the difference and gets confused. I thought that was a relic of old switches as most these days can tell the difference between a crossover and straight cable and compensate to work with it but it is possible that yours doesn't.
It shouldn't be anything to do with wake-on-lan and magic packets, those address the network adapter by its mac address (a packet of data containing the mac address 16 times if i remember correctly).
If you can borrow one, try another switch / router and see if the problem persists.

[#8]

"AutoUplink™ technology automatically adjusts for two common types of cables" - on the switch. 

[#9]

Slight difference though, you're talking of an uplink. Besides, I had a router once that claimed it you must use the correct type of cable as it did not auto sense. Then in the manual it clearly states that it supports MDI / MDIX - plugged in a crossover cable knowing it would be wrong and sure as eggs are eggs, it worked.
My current router supports upnp too. I still can't open ports on it from my PC though and none of my programs can either - not even using the windows firewall.
Feature lists are all well and good but the features do not always work as advertised. Just because it claims to have autouplink doesn't mean that it actually works properly.

[#10]

If you have tried different cables, different ports, checked both PCs are using DHCP/have different static IP addresses, then I suggest there is a fault in one of the PCs - possibly an earthing fault at one of the pillars. If you can get a third PC (or laptop) connected in, that may give some more information.
I have seen a similar problem to this, but it was caused by an "auto-switch" that connected one of two PCs to a single port and would "stick" due to the WOL function providing power except when the PC was powered off "at the wall". I have not seen it occur with an auto-sensing switch (though the cheaper ones go mad if you plug a cable into two sockets  )