Network card driver problem?  

Hello!
I have a very wierd problem. When I start the computer, everything goes fine until the OS starts loading network connection. I get the "device plug in sound" and then everything freezes completely. I have to wait about ten seconds and after "device unplugged sound" the computer works, but only for five second or even less. This continues for about 10-20 minutes everytime I boot up the computer.
The problem does NOT occur if I plug of the lan cable. That is not the solution though because the problem continues immediately after I connect the lan cable back. I have tried system restore, installed different network drivers but with no luck. What could be the problem, maybe it is some hardware problem?

Problem solved. There was a problem in a router. Rebooting the router fixed the problem. Usually most problems go away when you reboot all your devices. This time I just had forgotten to do that...