A set of useful troubleshooting tips. None of these should be needed of course.
Andreas Junghans In response to David Whitehead's network problems after the 10.3.8 update:
I've had network problems in the past after some OS X and security updates. Apple's Mail and Safari would not be able to connect to servers while Mozilla would continue to work just fine. What solved the problem every time was rebooting the machine (a second time after the mandatory reboot when the install is finished).
Regarding Tim Wojtyniak's question about the applications in the 'Open with ...' menu:
Each OS X application contains information about the file types it can work with. Whenever an application is launched or simply clicked on in the Finder, OS X updates the so-called 'LaunchServices database' with the new information. Among other things, this database is used for providing the 'Open With ...' entries (similar to the Windows registry, but only used for file associations).
As detailed here, you can completely rebuild the LaunchServices database using the following command in a Terminal:
LaunchServices.framework/Support/lsregister -kill -r -domain local
-domain system -domain user
This command first flushes all entries and then rescans the usual folders that contain applications. For each application found, the corresponding file associations are added to the database. After this procedure, deleted apps should no longer appear in the 'Open With ...' menu. In case you have some applications stored in custom locations (e.g. '/Productivity Apps'), you have to launch them once to restore their file associations.