Vista - Ethernet sporadic

I recently built a computer with an ASUS motherboard with onboard ethernet.
The ethernet adapter listed in the Device Manager is:

Realtek RTL8168/8111 Family PCI-E Gigabit Ethernet NIC 9NDIS 6.0)

50% of the time on boot I am connected to my 3Com 10/100 network. the other
50% the PC is not. IE 7.0 cannot connect and the PC cannot see the other PC's
on the network. When I open IE 7.0 and am not connected, I get a dialog box
that recommends a repair by seeing a new IP address or by repairing the
current settings. Either solution works. I can close and reopen IE 7.0 and am
connected. Also the PC can now see the other PC's on the network.

I think it is a problem with the Reaktek driver but I have the most recent
update.

The Vista PC is a test case. The other PC's on the network run Win XP-SP2.

Does anyone else have a similar problem or suggestion?
--
malcolm