getting incorrect “network cable unplugged” message

I just installed a wireless router (LinkSys model BEFW11S4 ver. 4) on my desktop PC. My laptop is able to connect just fine without interruption in any room. Although my connection on the desktop is never truly interrupted, it keeps flashing “network cable unplugged” immediately followed by the “connection established” message. I’ve had a techie friend of mine walk me through several possible solutions, but none have worked. What the heck is causing this message?

Thanks for any help.
Nathan