Irritating Router Problem - Help!

I share an Internet connection with my landlord via a router. We have a couple of issues that are bugging the hell out of us, and we need to get this sorted!
I have XP Home with an Edimax 10/100M Autosense ethernet card model number EN-9130TXL, he has MacOSX on a G4, we are both going through a DLink router. The main problem is that sometimes the router kicks over, and we have to switch it off and on again to get it working again. It mostly does it when I try to share files/play games/watch video with an MSN buddy through Messenger. It also does it when I unplug my ethernet cable to use it on another computer (I build them for mates etc).
He seems to think its something in XP conflicting with it, as he has had other PC's on the same network before I arrived here, and had no such problems. What can be done about this?

You need to determine what is going on with the router when it "kicks over"

Can he IE into the Dlink when its "kicked"?

There really isn't anything a pc or OS could/should do to lock up the router. It is usually a router problem from what you describe.

Another route to investigate is a saturated router. If you have a virus broadcasting that can jam up a router. But the lites are solid or seriously flashing on the router so you would have a clue.