This may have been mentioned in a comment here at some point, or even in passing in a story. But it bears repeating as a full hint of its own.
If you are having difficulties in OS X, there are many ways to troubleshoot. Some are quite similar to the OS 9 style of troubleshooting - disable applications that load at login, try trashing preferences in your user's preferences folder, test without third-party hardware devices attached, etc.
However, there's a new tool you can use thanks to the inherent multi-user nature of OS X - try creating a new user and see if the problem persists. This can be especially helpful when troubleshooting an application problem. When I had a problem with mail quitting on launch, I used a second user ID to determine that the problem was only with my primary user - the new user was able to launch Mail perfectly well. This narrowed the scope of the problem to something (preference file or bad application) within my primary user's space. It turned out to be a corrupted Address Book database file.
So think about creating a second user ID for use in troubleshooting OS X - it doesn't take up much drive space, and it could help save a bit of time in identifying whether you have a user-level problem or a higher system-level problem.
If you use your G4 for numerical computation, this may be of interest to you. I've had a page with computing tools for OS X for some time now. I just added some information and analysis on how one could harness the full power of a dual G4 for numerical work.
The page is about using AltiVec and using both processors in parallel for C and Fortran codes. The speed gain upon using both parallelization and vectorization is huge. On my tests, it varied between 4x and 10x improvement!
[Editor's note: OK, my head is spinning from just reading some of what Gaurav has put together ... but I figure his information may be of use to some of you, so here it is!]
In applications that support scroll wheels (all Cocoa apps, some Carbon apps), when you pull down a menu, you can use your mouse's scroll wheel (if you have one) to scroll through the menu's choices. Also, for the duration you're in the menu, your scroll wheel will act like a button when you press down on it.
[Editor's note: Cool trick! I found that the button behavior was flakey (it's ignored in Mozilla, for example), but the scroll wheel worked everywhere I tried it in supported apps!]
I switched to OS X two days ago and got crazy when I found myself pressing the function keys to reveal my app actions -- I feel invalid without F1-F12 in Photoshop and Flash. I was searching the web for that issue but couldn't find any solution (not even the problem mentioned...) Well, I finally found one...
Boot into OS 9, open the Classic control panel "Keyboard" and change the prefs here. Booting back into OS X, the function keys are functions keys again! Woohoo!
[Editor's note: I'm almost positive we had published something along these lines at some point in time, but I can't seem to find it at the moment...so apologies in advance if this is a duplicate!]
A German guy has done it ... the first USB webcam driver is now available, but only for the Philips ToUCam Pro. I hope that other cameras will follow soon as this is written as open source. Read about the 'wc' driver and its current status on the wc home page.
[Editor's note: I used Oculus for OS X over the holidays to drive our FireWire video camera as a web cam, and it worked perfectly. It captured an image every second to the hard drive, and uploaded an image every 90 seconds to our website for a couple of hours. The Oculus site lists some USB cameras as supported, but I have no idea if they work in OS X or not.]
A while back, I noted the improved Apple Knowledge Base and its useful options for learning and troubleshooting OS X ... here's one example of why I find it so valuable.
After returning from Macworld Expo, I was browsing my saved "What's new in OS X" search for new or revised OS X documents. One of the items listed was Troubleshooting a Startup Issue. This article contains a number of troubleshooting steps that may help resolve startup problems that include a blue screen, gray screen, flashing question mark, kernel panic or other issue. So if you're having startup problems, give the article a quick look!
And if you haven't built yourself a Knowledge Base page yet, it's well worth the effort. The new Knolwedge Base is the best way I've found to stay connected with official Apple information releases regarding OS X. I certainly have no intention of repeating everything they publish there on macosxhints, but I will try to note when particularly interesting articles are released.
My system became slower and slower and bringing up the font menu in Cocoa apps was very slow - taking between 5 and 10 minutes (beachball-cursor, even the dock was incredibly slow).
I checked out the font directories but couldn't find anything strange. So I copied all the fonts from my user's font folder (~/Library/Fonts) to a new folder, restarted my machine, copied all the fonts back and restarted one more time (not sure if the restarts were necessary). After this, my machine works fine as before.
[Editor's note: I have no way of really testing this myself, so it's published here as a possible troubleshooting tip for those that may be experiencing slowdowns in OS X.]
I noticed last night that my desktop machine had "Customize", "Gear", "Connectivity', "Nuts and Bolts" and "Misc" in place of the normal names within the System Preferences window. The normal names are "Personal", "Hardware", "Internet & Network", "System", and "Other". I'm not sure how these were changed on my machine; I honestly do not recall doing it myself (and I searched the site for a hint about renaming system prefs and came up blank). Perhaps some third-party preference panel that I installed and removed changed them at some point. If you have some idea of what might have changed this, let me know (out of curiousity more than anything else).
In any event, noticing that they differed from the official names as seen on my iBook, I set out in search of what was controlling the names and discovered that they are relatively easy to change.
I created a one-second movie using the QuickTime 'DVCPRO-PAL' Apple codec. If you attempt to play it with QT Player 5.0.2, you should get the standard, "QuickTime does not have the necessary software . . . " message. Then QT Updater should launch and download the new 'QuickTime JPEG Update' and 'QuickTime DV Update' extensions.
This should work for both Classic and OS X. Just play the movie with each version of QuickTime Player. In Classic, these will appear as extensions in the System Folder -> Extensions -> QuickTime Extensions folder.
This seems to be the only change in QT 5.0.4. These are the same components included on the new FinalCut Pro 3.0 installer CD.
[Editor's note: It appears this movie has been pulled from the referenced webpage. I'm leaving the article here as some of the discussion below contains useful information.]