MN-700 Router won't connect to the internet

I have a 2 computer network in my house. I use an MN-700 router on the
desktop connected to the modem, and a wireless adapter on my laptop. The
router has gone down before, and does periodically, but normally I can do the
typical reset and troubleshooting steps, and it will fix the problem. It
went down last night, so I tried doing the typical steps, and nothing would
work. I finally called my ISP, to see if maybe it was the internet down in
my area. They told me to do several things, all of which worked with just
the modem connected straight into the computer, and bypassing the router. As
soon as I plug the router back into the modem, and the computer into the
router, it almost instantly goes down. I finally gave up and thought maybe
it just needed time to reset itself, but it was still down this morning.

I called MS Tech Support, and they wanted me to pay $35 to tell me the
problem, but I didn't want to pay that knowing that I could find just as good
and probably better answers myself. I've read through the newsgroup that the
MN-700 is just not that reliable after several years (we've had ours since
2003), so is just time to bury this one or is there something I can do to
prolong having to buy a new one a little while longer?

Thanks for any help!!