This error was a real nuisance. I should have known though. This was one of those things I have seen before and just wasnt thinking. I was trying to ping the core switch when the 3550 gave me this error: "% Unrecognized host or address, or protocol not running." Well, if you looked at my config, you would see that I had no ip address on vlan 1 (or any vlan in the config). Turns out that if you put an IP address on vlan 1 and then try to ping, you will overcome this error. Interesting enough for me to post it, as Im sure someone will benefit from this.
config t
interface vlan 1
ip add 192.168.1.1 255.255.255.0
exit
