I encountered a problem recently where Word would not save, and Photoshop and other applications would not launch after an upgrade to 10.6 from 10.4.
Essentially what I needed to do was reset the printing system. While this was easily achieved in 10.5/10.4 it's not so easy in 10.6 especially when CUPS would not launch.
There was no access to the Print & Fax prefpanel or to the local webpage at http://127.0.0.1:631 so after a bit of hunting I found the following fix.
To reset the print system without using the Print & Fax system preferences, you can follow these steps in the Terminal. This can be done either locally or by logging in remotely via an SSH session.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20110117121647762