Question : Problem: Router to Router connection and config

Hello, I am trying to connect and configure two Cisco 1721 routers together using a crossover cable from E0 to E0 but no matter what I do I get "line protocol is down". I have verified that both are using the same encapsulation types with show ip int brief. Below are the configs. I thought this would be simple but apparently not :( Anyone have any advice? (PS I pruned the configs to show only relative lines)

RouterA#show run
Building configuration...
!
interface Ethernet0
ip address 10.0.0.2 255.0.0.0
half-duplex
!
interface FastEthernet0
no ip address
shutdown
speed auto

--------------------------------------...

RouterC#show run
Building configuration...

!
interface Ethernet0
ip address 10.0.0.1 255.0.0.0
half-duplex
!
interface FastEthernet0
no ip address
shutdown
speed auto


RouterC#show ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 10.0.0.1 YES manual up down
FastEthernet0 unassigned YES manual administratively down down

-------

Also, I am getting this message every xx seconds:

%PQUICC_ETHER-1-LOSTCARR : Unit [dec], lost carrier. Transceiver problem?

Cisco's website of course says this:
" Explanation The Ethernet 10BASE-T cable is unplugged.
Recommended Action Reconnect the 10BASE-T Ethernet cable."

However, I am not sure if is referring to the FastEthernet0 port that is unplugged or to the Ethernet0 that I am trying to connect. The Crossover cable I am using to directly connect the two routers looks correct and was tested with a Fluke.
Any suggestions?

Answer : Problem: Router to Router connection and config

To test the Router ports, try connecting a PC NIC to each routers ethernet port and see if the interface comes up.
My first guess would be the issue was related to a speed or duplex mismatch.

Try setting the interfaces to full duplex: "duplex full"
Also, (silly question) make sure you are plugged into the Ethernet Interface and have not accidentally plugged into the (shutdown) FastEthernet Interface.

Also, may I ask why you are using the Ethernet Interfaces as opposed to the FastEthernet interfaces?

The error you are getting every few seconds as you ave indicated above does refer to the Ethernet Interface, not the FastEthernet interface as described by the "ETHER" part of the error.