We are running Windows 7 Enterprise, fully patched on Dell Optiplex 745, 755, 760, and 980 computers and I can duplicate this on all of them, plus my personal Gateway tablet pc's wired and wireless cards. This happens with the latest Intel drivers, the Dell/Intel drivers that shipped with the computers, and the old generic MS drivers that Windows 7 uses if you delete all of the other drivers.
These are multiple computer models, manufacturers, driver dates, driver producer, and bios versions. The only constant are Intel nics and Windows 7.
I go into Device Manager -> Network Card -> Power management. Check the boxes that we want. Close Device Manager. Reopen Device Manager to check that the change took. It did. Reboot. All Power Management settings for the nic are now unchecked.
We just want to instal the drivers. We don't need or want all of the snmp management features and other software that comes with the Intel download.