Ethernet Dropping Out in both OS X and Windows

I purchased a brand new iMac 2011 model last week, but have found that the ethernet is faulty. I'm still not sure if this is a hardware or software problem, as after i reboot, the ethernet port works fine, for a bit at least.

The exact same problem also occurs when i am running Windows 7 inside boot camp. The only way to make ethernet work again inside Windows is to reboot, and then reset the PRAM. (holding Command + Option + P + R).

To fix the problem inside OSX(temp), open up terminal and type:

$sudo ifconfig en0 down

$sudo ifconfig en0 up

This restarts the ethernet card, but the problem still comes back after a small amount of time.
I need this fixed immediately because i require Ethernet transfers for large files.

Also, please note that the problem does not occur on my MacBook Pro, which also runs OSX 10.6.7