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Granted, I’m an Apple partisan, but this recently revised knowledge base article on “Isolating issues in Mac OS X” is an extremely well-written guide to finding out what part of your Mac OS X system is actually responsible for causing whatever problematic symptoms you’ve noticed. Isolating the problem is often the hardest part of troubleshooting, and this is written clearly enough that any Mac OS X user can follow the steps. If I were still training support staff, I’d use this a an introduction to troubleshooting.
And, while I’m at it, I should also point out this Apple article on Mac OS X Keyboard Shortcuts.
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