I'm installing Win 7 on a Dell Dimension E520 that is equipped with a built-in Intel 82562V 10/100 NIC. I've experienced the same problem with both 32-bit and 64-bit versions of Win 7. I've installed the latest driver from Intel for each version.
The problem is a random slowdown/stop of all network traffic. The system will work fine for hours, then suddenly a download stops right in the middle. The only solution seems to be rebooting. After a reboot it will probably be fine and sometimes (like tonight) I can go several hours and never have a problem.
This problem also occurred in the 32 bit version when I installed a 3Com 3c905 NIC and disabled the onboard Intel NIC. So I'm really puzzled and the event logs contain no entries that provide a clue.
How can I pin down if this is a hardware problem (and what component it is) or if it is a Windows problem?