Thanks for the quick response, Krit.
Q: What kind of router is it?
A: It's a D-Link DI-514 wireless router.
Q: What have you done to fix it?
A: I haven't done anything to router specifically. Not yet, at least. Aside from the System Restore and the Last Known Config. attempt (neither of which worked)- nothing to the router. But all of the lights on the router are on, and flashing as they should be (as verified by the owner's manual and my ISP's tech. support).
Q: Is Windows used to configure the wireless connection, or software?
A: Windows, I believe. I called D-Link the other day (who recommended reformatting XP) and they told me that the router doesn't use any particular software. It's plug, configure, play.
As I mentioned before (and hopefully my post wasn't too confusing), modem's working, and so is the router- the two just don't seem to be "talking" anymore. :/
As for the Start>Run process, I did exactly what you said on my father's desktop PC (remember- this is the one that doesn't work anymore) with everything set up the way it should be. Here's what it says:
But! When all I do is unplug the Ethernet cable from the router and into my personal laptop directly (remember- my dad has a deskptp PC, and I have an Acer notebook), I get this on my dad's PC:
Any ideas?