1500 work PCs...network card disabling after long period of sleep?

We just got in 1500 Dell Optiplex 390's for our school district. We just deployed them at 13 different schools, and we thought all was well. This is the first machine we've installed in the schools with Windows 7, so it may be something with that.

The problem is that after some of these sleep, after waking, it's not finding the network. The network icon in the corner is just spinning. IPCONFIG sometimes yields an old IP. If I check the network card properties, it is "DISABLED". Only way to fix is to restart PC.

Another similar problem is that sometimes after a cold boot, it won't catch the DHCP network somehow. It'll give a 169.254.x.x address. If I let it sit for about 10-20 minutes, it will randomly get an IP address and jump on the network.

Not sure what is going on here. We have the "turn off this device to save power" enabled on the network card, since that is the only way we're able to check "allow this device to wake pc" option. We need to be able to remotely wake these machines (WOL) from sleep. I'd imagine this is pretty standard practice.

I may not be in charge of our network, but our setup is rather simple (and no one here can figure out why we're having these issues).

We're running Windows 7 32bit. Novell Windows 7 Client (Active Directory is coming in a few weeks).

Any suggestions? It seems as if Windows isn't re-enabling the network card upon wake. In other instances, cold boots sometimes don't work. "Server/Tree not found" on the Novell login, and then after I login as workstation only, I have to wait 10-20 minutes for it to find/catch the DHCP server. This is happening at multiple locations - all with the new Optiplex 390 machines. Other school locations are fine.

Any suggestions?