You should investigate the two possible causes it lists:
1) Port already in use: There could be another application that is listening on this port. Try running netstat -na at a command prompt and see if this is the case. The other possible explanation for a port problem here is that the port is < 1024, meaning that it's a privileged port, you might have permissions issues with this. Try it with a port > 1024.
2) No Write Permission to orb.db: The orbd program writes a log file called orb.db that it uses to recover state if it is restarted. The default behavior is to store this file in the same directory as the orbd executable. If you do not have write permission to the directory that the orbd.exe file is in, then you will get this error. If this is the case, use the -deafultdb option to specify a different directory that you can write to. See here: http://java.sun.com/j2se/1.4.2/docs/guide/idl/orbd.html