Open Transport
Lots of the software problems causing users to freak out involve extension conflicts. Fortunately, Apple is attempting to turn all control panels into applications so there will be less likelihood of control panels but there will always be extensions and, no doubt, new weird INITs like contextual menu items (OS 8.1). Inits are types of extensions which usually load with the little puzzle icons at startup. Control panels are applications that usually affect the operation of the system, for example the Date and Time control panel allows you to adjust the date and time of the system clock.
The first step in determing whether an INIT conflict is present (which means problems with control panels, extensions, and stuff like that confusing the computer) is to restart with extensions off (hold down shift while booting) and see whether the problem happens again (unless you're sure it's an INIT conflict problem). If the problem does not occur with the extensions disabled, then it is an extensions conflict. If the problem persists, then it is probably not an extensions conflict.
Control Panels
TCP/IP
Implemented in: Open Transport
The control panel in charge of what your IP address is and, in general, your identity on the network. (reference to SCIC pages here???)
Appletalk
Implemented in: Open Transport
The control panel in charge of whether and which network you are connected to. Opening it up will tell you if it's on (if it opens, it's on) and you should set the little drop down thingie to "ethernet" and the local zones should read something like "ACNS" or the department that you're in.
~ATM
Implemented in: Adobe products (usually Acrobat Reader)
The control panel from hell when it comes to conflicts. If weird things are happening to someone's computer, a good idea is to check the version number of the ~ATM control panel to make sure that it's at least 4.02 (as of 11/5/98). It smooths fonts, which is usually not good in terms of compatability, and makes it so Acrobat works so the user can read ".pdf" files.
Date & Time
Implemented in: System 7+ You can set the date, time, and time zone on your computer. You can also set how dates and times are displayed. A good place to go to set a user's clock correctly. Also is sometimes buggy.
MacTCP
Implemented in: less than System 7.5.3 You can control how your computer is connected to network services (such as the Internet) that use TCP/IP protocol. Does not work with Open Transport. In fact, I recommend installing Open Transport from Celeste ASAP because it is, overall, a better protocol system.
Extensions
Open Transport
Implemented in: 7.6
Versions: 1.0, 1.1, 1.1.1, 1.3(.1), 2.0, 2.6