Once you've eliminated the obvious and the environmental and tried your quick fixes, there are two methods that can help you isolate the cause of the problem quickly. Both use the process of elimination to reduce the variables. They are the one-step reductive and split-half search.
In the one-step reductive method, you remove all variables of the system one at a time. If the first component you test doesn't eliminate the problem, then you move on to the next logical cause. This method works best when you have a lot of clues to the source of the problem and a strong hunch, based on experience, observed behavior and perhaps help from a colleague.
Let's say that FCP can't capture video at all, but operates fine otherwise. You eliminate the quick fixes and move on. Having asked the right questions from the first section of this lesson, you realize that Norton Antivirus was installed earlier in the week. Quickly, you go online to the Apple Knowledge Base Web site and a couple of the other popular FCP Web forums and do a search that confirms that Norton Antivirus causes conflicts with FCP capturing.
At this point, armed with such a specific lead, you can make a direct attempt to correct the problem. You uninstall Norton Antivirus, restart the computer, return to FCP, and attempt the capture again. Voila, the problem is solved.
This is a great situation for using the one-step reductive method, because you have so much confirmation and corroboration that matches your situation. If you keep up with the Knowledge Base and the online Web communities (and perform regular maintenance on your system), most issues you encounter can be solved this quickly.
In cases where you have little specific information about an issue, turn to the split-half search. Perhaps the issue is as-yet undocumented by Apple. Perhaps it is so intermittent that you have yet to develop any clues about the source. Perhaps there are so many variables that eliminating them one by one just isn't an option.
Using the split-half search method, you test and eliminate whole groups of components at a time.
Imagine for a moment that you have six USB devices and a FireWire scanner on your station, one of which is causing an intermittent issue with your third-party capture card.
Finding the problem device is difficult because of the intermittent nature of the problem. And imagine if the problem is actually caused by the simultaneous use of two or more of the devices, so that it only occurs when they are both present.
Clearly, you wouldn't be able to discern the problem by disconnecting the devices one at a time. But you could disconnect them all and then reattach three of them simultaneously (let's say starting with the oldest, the most reliable, or the ones which use Apple's native drivers) and then proceed with your work. If the problem doesn't occur, then you know the problem is not with the first three devices.
You write this all down, disconnect the first three devices, and reconnect the last four. If the problem reoccurs at this point, you have now narrowed the issue down to one or more of these four devices. Now you can perform another split-half search of these four USB devices.