hi, in my network most of computer had asrock 945 g31 series

"Reltek RTL8102E/RTL8103E family PCI-E fast ethernet NIC" is inbuilt nic card in it.

the problem is most of times computer shows unplug and re-plug of nic card automatically without touching the network cable.. I checked the cable that's ok and I also checked the shared switch (DGCOM) but it's also ok . And this problem is not only 1 computer most of all computer but not in same time. And some nic card hang and stop working in that time if i unplug the wire computer still shows the wire is pluged in.

what is the problem is there any problem with this series of mother board?? what is the solution of that

I would check your switch/router first before looking at the PCs.