A quick lesson in Mac tech support for a few minor emergencies. Try www.macfixit.com or www.macintouch.com for more specific help.
My application isn't working!
Delete "System Folder/Preferences/MyApp Prefs". Try running it again. Works for the system preferences too — though be careful to write down your internet settings before trashing them.
It keeps crashing!
Some detective work will be needed. Does it crash in a specific app? After using a specific app? When scanning? Copying files to a PC server? Check for updates on all your software providers, and try knocking out strange extensions a few at a time with Extensions Manager. Don't disable Apple extensions, and use a tool such as InformINIT or Extension Overload to tell you what every extension is and what it does. Find new versions of existing software by checking www.versiontracker.com regularly — it has a search tool too.
Generally, the fewer add-ons you have, the fewer problems you have. Certain USB extensions have been a problem for me, though not for most other people. Bad fonts, or too many fonts, can often cause weird problems. Taking out Microsoft extensions is pointless as they'll be reinstalled next time Word/IE/OE runs. Your mileage may vary.
If all else fails, you can reinstall the system.
How do I reinstall the system?
Using the system disc that came with the system, or any of the G4s, you can install a clean system or just reinstall over the existing setup. Clean is good if you're having system problems. Contrary to popular myth, a Mac with minimal system extensions running standard applications will only *rarely* crash. Just don't use unstable add-ons like Ram Doubler, Suitcase, etc.
However, reinstalling a clean system can kill all your preferences, so make sure you back up the goodies first. The installer will move your old system and rename it to "Old System Folder"; don't delete it until you've:
Don't do these things by moving whole folders. A clean system is a rare joy; take this opportunity to clean out crap you don't need; whittle down any fonts you haven't used in months. Create "(disabled)" versions of Fonts, Extensions, and Control Panels folders, and throw everything you used to use in there. You might still need it.
Network basics
Two basic networking protocols on Macs: AppleTalk and TCP/IP. Both useful for different things.
AppleTalk is old, inefficient, but very handy for instant, simple, Mac-to-Mac networking in small groups. Drives appear natively and you can copy safely with reasonable speed.
TCP/IP is newer, more flexible and more capable. WWW and Email services use it. Our PC network uses it, as does DAVE, which lets Macs access the PC network. AppleTalk can also run over it — AppleTalk over IP.
How to get to the network? Three options.
Use the Chooser to access AppleTalk or DAVE Client PC drives in a Mac-like way. Preferred. When you have a range of drives to choose from, you can command-click to select a set of volumes. Don't use the checkboxes beside the drive names; that's for autoloading at startup, and can be difficult to disable if/when the drive moves servers or is renamed. Just use aliases and mount when you need to. (To stop a machine from loading AppleTalk servers at startup, trash the file AppleShare Prep from the system folder, or delete the aliases in the Servers folder on newer systems.)
Use the Network Browser to access AppleTalk or AppleTalk over IP, called Network Services. IP is slower to find machines, even though the Macs have static IPs. Don't know why. Just use the Chooser — it has the same results but is faster.
The DAVE program can access PC drives in list view only, without icons, and will only let you copy files, not move them. Faster in certain circumstances, such as looking around the US server, but inconvenient in others. For example, it does support the "option-open to close this window behind the new one" shortcut, but doesn't support the "command-click in titlebar to go backwards" shortcut. So if you open the wrong folder, you've lost your path and can't get back. Sometimes slower than the Chooser equivalent, sometimes faster.
Passwords are a necessary evil in all these options; we try to keep it simple. We do it the "bad way" by allowing people to log in with full control over the machine. Since we all trust each other, that's fine, though we should limit it a bit. A "projects" folder might help, since captures and renders go everywhere on the G4s, it's difficult to maintain the separation completely.