Tonight I powered up my desktop PC only to find that I had no Internet connection. In fact, I had no LAN connection at all – it turned out that my PC had been assigned the dreaded 169.254.x.x IP address which is a default address that gets allocated by Windows if DHCP fails to get allocated an address from your router (bear in mind that I’m connected to my router via ethernet; no wireless involved).
I tried rebooting the PC, rebooting the router, uninstalling drivers etc., winsock resets, ipconfig /renew etc. – nothing worked. I connected my laptop via ethernet without a problem, and even connected the PC via wireless.
So, I thought the problem must be with the LAN on-board my PC. I then found a post which suggested turning off the PC, removing the power cable, and holding down the power button and reset switch for 10 seconds.
Sure enough, it worked! No idea what that does or why it worked, but I now have a working internet connection. Wonderful.