We recently replaced our 4006 with a 4510 (all gig ports). I have had a few machines with Intel 82567 gig cards that are acting up.
The one I am working with now will show connection for 4 seconds and then give a "net cable unplugged" error.
I have tried all the troubleshooting steps I can think of:
Set switch port and NIC to same port speed/duplex (everything from 10/half up to auto 1000).
Tried different ports and cables.
Upgraded Bios and nic drivers.
Went down the list of steps in the Cisco troubleshooting guide.
Perhaps one of you has had the same problem and found a fix?