Cisco Firewall :: Unknown Error On ASA 5505?

This might actually go into Networking Basics because of the nature of the problem, but I tossed it in here because of the Cisco product involved. Long story short, I need to do some detective work to figure an apporpriate IP address for a NIC.I recently started working at a company with the ASA 5505 and I need to upgrade the software image on a bunch of them. There's already a computer set up with a TFTP server and Hyper-Terminal to do it. I'm trying to use the CLI update procedur[URL] but when I get to the beginning of the actual transfer from the TFTP, I get stuck at "Accessing" and then the connection times out with the message "Unknown Error".The only thing I can think of is that somehow the ASA is not making it all the way to the TFTP server, probably because the IP address settings on the NIC for the computer is set wrong. I say this because in the config file provided me, the ASA is given an address X.Y.Z.1, subnet mask /24 (where all the letters are constants) and the TFTP server has an addess in its software config of X.Y.Z.10 mask /24, but the NIC on the computer is set to A.B.C.105, which is an entirely different network.I need to figure out what I can make the NIC IP address so I stop getting the error. I tried a couple of different X.Y.Z.x addresses, but haven't gotten anything yet.