ERROR 1201 (HY000): Could not initialize master info structure; more error messages can be found in the MySQL error log
Could not find target log during relay log initialization
I think this happened because I changed IP numbers on the replicating server. I issued the command "RESET SLAVE" (though I don't recommend you doing this) and was then able to start the slave again.
Now it seems the replicated server is going through the motions to synchronize with the master.
That wasn't working right so I ended up redoing the entire thing manually following the howtoforge docs. Works now. :-)