Stuff breaks down.... DLINK is better than LINKSYS.
Early this week the two laptops were stacked one on top of the other. I was using the top one. The harddrive hiccupped, and I thought it was gone (it probably does need to be replaced). It made a funny clicking noise and then stopped. Everything froze, incl. the mouse cursor. I did a hard power-cycle. After the "HP" screen (built into the BIOS), the screen displayed "Operating system not found."
My theory: If the hard drive, spinning at 5400 RPM, were to suddenly stop for some reason (as sounded like happened), the magnetic pulse from the motor would send a sudden shockwave of induced current into the wiring of the WIFI cards, located immediately below the hard-drives. Since the machines were stacked, it would have penetrated outward to the lower machine as well, apparently with enough strength to cause damage to the transmission circuitry. A "mini-EMP".
Incidently, though I assumed that HD was toast, I am using that very machine at this moment to type this message with the same HD.