Laptop will not boot, repeating PXE-E61

Hi All:

My computer: Dell laptop Studio 17/1745. Windows 7. Bought Jan, 2010.

A couple of days ago, I ran a complete virus scan (McAffee) on my laptop. Since it takes a long time, I left to do something else. While I returned about 1 hour later, the computer screen was blank, with this repeating messages:

Intel UNDI, PXE-2.1 (Build 082)

Copyright (C) 1997 - 2000 Intel Corp.

This product is covered by .....(a series of numbers)

Realtek PCI Express Gigabit Ethernet Controller series V 2.26 (090219)

PXE-E61: Media test failure, check cable

PXE-M0F: Exiting PXE ROM

This messages keep repeating. I tried to reboot but same messages show up and nothing else happens.

I run diagnostic test (takes about 40 minutes) and no error message.

I have tried Knoppix and was able to access the hard drive and save some files that I can fit on my flash drive.

Some files (like family video files) are simply too big to save to flash drive. I hope I can fix the problem without losing all these files.

Any suggestions?  Thanks for your help.