Time Machine - Unable to use

When I start TM and select an attached SATA II hard drive as the backup
device I get the following message:

"Time Machine could not be configured
The built in network interface could not be found"

This is confusing to me as I don't understand why TM would need a
network interface to do a backup.

Way back when I first installed ver 10.5.2 Kalyway distro I was prompted
to do a backup with TM and I chose the SATA ii hard drive that i'm
trying to use now. The backup then was successful,

When I installed the IPC 10.5.6 distro I again got the option to do a backup
but I opted not to do it till I was sure I had a functioning system.

Now every time I try to run TM I get the message above.

All I want to do is backup my working system to an internal SATA ii
hard drive.

Any suggestions?