I have to agree. I had to take my post down until we figure this out. ng, it may not be that the network's becoming 1Gb/s that changed things. We really don't have enough information. Alex didn't tell exactly what "upgraded to a Gb network" means.
Was it just changing the switch? Did he upgrade the Ethernet cables? NIC cards?
All of which would have to be Gb capable. It is possible that only the switch was changed, and the switch was faulty. Could it be he was using a hub, God forbid, and went to a Gb switch, again limited by the other hardware mentioned above. The NIC cards could have been 10Mb/s at half duplex.