LARTC - Aug 2006 - RTNETLINK answers: File exists .. Network is unreachable

I am a Linux novice.

I have set up a Linux Router that is running the 2.6.15-1.2054_FC5 
kernel.  I boot to an initial router state and then I experiment with 
various "tc" commands by executing them at the command prompt.  I 
reboot often to restore the initial state.  When I booted up the 
router today I got the following messages during the boot process:

	Bringing up interface eth0:
	    RTNETLINK answers: File exists
	    RTNETLINK answers: Network is unreachable


	Bringing up interface eth1:
	    RTNETLINK answers: File exists
	    RTNETLINK answers: Network is unreachable

Will someone please enlighten me as to what is kind of problem is 
being indicated by these messages?

Thanks,

Bob