The pc world guy is right

you can connect to network with Crossover cable, so there are no problems with your network card.

I guess there's something wrong in the port that you used to connect to network. Maybe your administrator changed that port's setting to uplink mode by mistake. you know, a port in uplink mode only accepts cross-over cable.

Although some network devices can detect correct mode for other devices connected to itself, it seems yours is not so smart.