Check to see if you have the correct drivers installed for the NIC card, if not the resinstall the drivers for it and make the that card it using the correct interrupt, which should be IRQ 10 or 11. If you have a SCSI controller make sure that it is not trying to use IRQ 11 because it takes this be default, if your NIC card is using 11 than this can cause conflicts as well. Just something extra to take note of.