needing help (best place I can think to put it)

I dunno if anyone here will know or whatnot, but this is really pissing me off, so here we go:

quick overview:
two comps, both on a network, connected to DSL, etc etc

one computer (not mine, thanx random-fluctuations-in-the-space-time-continuum), suddenly, cannot connect to the internet......it just.....stopped....I mean, christ, in the middle of being used.....the ethernet card is still there, and it can still be found in system....at first I thought it was a winpoet thing (cause it uses PPP to connect) but I uninstalled and then reinstalled it......and it SAYS it is connected, but all you get is that stupid DNS error, page not found, on any place I try to go.....and the MODEM wont work either! which is REALLY confusing me......and theres nothing wrong with wires (and anyway, the modem doesnt use the dsl line) and THIS comp can still use the DSL, and like I said they are both on the same network

and the motherboard cant be broke, cause like I said it still finds the card (which is reported as being ok) and its a freaking new one anyway so it better not be broke

the ONLY thing I can think of is that somehow, installing the newest realplayer (again, not my comp....Id never take that trash on mine) somehow managed to fark something up.....but I dont know why

I also tried reinstalled windows (not that it ever works) and it didnt work.....so for GODS SAKES HELP ME I AM DYING DYING I H8 COMPUTARS