It's probably old news, but for completeness...

[link|http://www.macfixitforums.com/php/showflat.php?Cat=&Board=Forum35&Number=352471&page=2&view=collapsed&sb=5&o=7&part=|This] page has a post (at the end) saying the 10.1 updates have to be installed as:

1. Install Security Update 10-19-01.
2. Install the Installer update.
3. Install the 10.1.3 Combo update.

I don't have any first-hand knowledge, but did some Googling that might help:

[link|http://www.osxfaq.com/man/8/ifconfig.ws|This] page at "OSXFAQ" lists various parameters for "ifconfig" and an explanation.

[link|http://www.info.apple.com/usen/macosx/tshoot.html|Here] is Apples' Troubleshooting Mac OS X page. Perhaps it'll help (nothing jumped out at me). [link|http://docs.info.apple.com/article.html?artnum=106718|This] Apple page lists the various install and reinstall procedures and warnings.

Hope this helps a bit. Good luck!

Cheers,
Scott.