Network cable unplugged... but its NOT!!

hi i have a huge problem here..
My pc is connected to 2 LANs. One thru my company LAN and the other thru another ISP using Broadband connection. They have separate NICs. The one thru the company like works jus fine. I'm having problems with the broadband connection. At first it keeps toggling between network cable unplugged and connected (freq apart 1 sec) and now, it jus shows that the network cable is unplugged every sec!!! ive checked with the ISP and they said that i am connected to their network, so the problem lies with my side. i've restarted my pc many times.. changed the cables, took out the microfilter, reinstalled the NIC, reconfigured the connection settings and it all doesnt work. when i tried to reinstall the modem thru its original NIC its not detected. but when do it thru the other NIC (one originally connecting pc to company LAN) it works. however, i still experience the same problem.. help??

Have you tried the problem NIC in a different pci slot? Sounds like either the card or the slot is the problem, and switching the cards in the slots would allow you to tell which it is.

Perhaps some of the pins inside the NIC are bent down too far to make contact with the RJ-45 connector. You've tried everything else, have you tried another NIC?

how many network devices under control panel->network connections? I've had trouble before if I disabled one of the 1394 connections on accident, or when configuring a network bridge. If you can get the "Internet Gateway" connection to show as active you should be ok.

***EDIT or try knoppix and use lspci or equivalent to see if the card is recognized on the pci bus.

I had a similar problem, turned out that my dog bit the cord which damaged it. A nice simple solution for my problem, good luck!