Realtek Wired NIC not showing up in device manager

I just finished reinstalling the o/s on a customer's machine from HP's original recovery discs.  The machine works fine except that it cannot connect using the wired LAN connection.  Looking at device manager, the wireless device is listed, but the wired device isn't, even with show hidden devices checked. I applied all the latest patches, including the BIOS updates from both HP and Microsoft.

The customer's original complaint was the usual slow system and intermittent ability to connect to the internet.  She said this started happening after she tried a "defrag or something" ;).  When I called her to discuss the issue I found with the wired connection she said that she always connects wirelessly and never used a cable to get connected to the internet.

My question is, "Is it safe to assume that there is a mobo issue that is keeping the wired device from appearing?" I would have tried clearing the CMOS but HP, in their infinite wisdom, wants you to disassemble the laptop just to get to the CMOS battery, which is beyond the scope of my work on this machine since the customer won't want to pay for the labor involved in the process, nor would she be interested in a mobo replacement.  Of course, if she wants wired connectivity there are some USB devices that she could purchase for a lot less than a mobo replacement.

Your thoughts?  Is there something I'm missing here?  Usually device manager or unknown devices will show when there's a problem with a driver, but in this case the device itself appears to be non-existent.