This happened to me today on an Acronis restored Small Business Server box (to different hardware using universal restore).
The issue is that the HP server that the image came from had HP drivers that ended up blocking the broadcom drivers on the Dell server I was moving to. The way to fix the issue is as follows:
1. Go into a command prompt.
2. type “set devmgr_show_nonpresent_devices=1”
3. Hit return.
4. Type “devmgmt.msc”
5. Hit return.
Once device manager has loaded, go to View, Show Hidden Devices.
You will then see “greyed out” old devices and network cards that you can remove.
Once you reboot all should be well.