Win7 freeze on loading when ethernet is connected.

I've had this problem with 2 different PCs and 2 different routers, here it goes:

My old PC was an E8400 with a Asus P5K mobo, whenever I would connect the Ethernet directly to the mobo windows would hard lock at the loading screen. If I would boot up and then plug in the Ethernet it would lock up with a sound loop between a few seconds to a few minutes later.

I was due for a router upgrade anyways, was previously using an old Linksys, so I opted for the D-link dir825. Same problem.

I figured something might be wrong with the mobo so I bought a cheap D-link Ethernet card and voila, problem solved!

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Now I have recently bought a new tower, an I7-2600k on a Asus p8z68 EVO with dual 6970s, and I am having the exact same problem.

There are 2 different Ethernet ports on this mobo and regardless of which one I plug the Ethernet into, windows hangs on loading. I have a wireless card installed and the PC runs flawlessly when using the wireless instead of hard wire.

I've gone out and purchased a TP-Link Ethernet card because they were cheaper than the D-Links but to no avail, windows still hangs on loading.

Any ideas? I dislike playing games on my wireless as my PC and router aren't close at all and I'm only getting 3 bars.

Thank you.