A NETWORK CABLE IS UNPLUGGED

For the last 3 days a popup is appearing on my screen, which says “A network cable is unplugged”.
I am surprised to see this message, as I only use the wireless for my internet. I have checked all the measures, provided in different websites, BUT all of them point to a network card. Surprisingly I do not have a network card installed on the system. I use win XP Service pack 3.
Is it due to some virus or my windows gotten corrupted? I will welcome any solution, which do not advise me the new installation of Win XP.
Thanks
