Blog post by Brent Amersbach, MacMedics Baltimore:

We installed 10.5.7 on a MacMedics MacBook that we use as a media center tonight, and it made a wreck of things. We did see some on-line chatter about the topic, but that seemed to have something to do with attaching a Mac to any display via DVI to HDMI cables. Regular DVI, fine. VGA, fine. DVI to HDMI, PROBLEM! 10.5.7 now apparently treats “HDMI” differently than regular monitors, and by differently we mean completely different. It wants to use oddball resolutions that add in overscan rather than the regular native resolution of the panel. To make it worse, the native resolution tends to disappear as a choice in System Preferences.

You can turn overscan off, but then your display shrinks to a rectangle in the middle of the screen with a border around it, even if the resolution you’re using is greater than native. The only fix is to use this handy piece of third party software called SwitchResX that comes in a full blown shareware version, and a free control panel version. The free version seems to do the trick. It’s mildly complicated, so be prepared to re-configure it a few time to get it the way you want:

1. Launch the app
2. Tab over to Custom.
3. Hit the + button to bring up a dialog
4. Fill in what your display’s native resolution should be
5. Enable the Use Simplified Settings checkbox and choose one of the options from the newly enabled drop down menu to its immediate right
6. Click Apply and then reboot. See if the resolution now appears in Display Preferences
7. Repeat steps 5-6 until one of those drop down choices makes the custom resolution appear as an option.

If none of the three “simplified” choices work, you may be able to get it working by tweaking the settings manually, but this is for very advanced users only.

In short, if anyone has a Mac attached to a TV or even a regular monitor by HDMI, you may want to avoid 10.5.7 for the time being. See this Apple discussions thread for more details:

http://discussions.apple.com/thread.jspa?threadID=2004318&tstart=0

Apple released the much anticipated 10.5.7 update to Mac OS X today.

PLEASE be sure to have a fully tested backup before installing the update. Also, unplug that backup drive and any other USB or FireWire devices before your run the 10.5.7 update. It is also a good idea to “restart” your computer BEFORE running the update, and install the 10.5.7 update before running any applications.

In general, MacMedics does not recommend that you install this update on a production machine. We also suggest that you not install the update the very same day it comes out, in case the update is recalled for any reason.

See our update warnings page for all of the things to watch out for.

http://www.macmedics.com/updates.htm

Also, see our full 10.5.7 post from a few days ago: http://www.macmedics.com/blog/?p=615

Word on the street is that Apple might release OS X 10.5.7 very soon (it was rumored to be released on Friday 5/8, but that turned out that not to be the case).

While the 10.5.7 Leopard update will be very exciting news, MacMedics DOES NOT recommend that Mac users install this update the day it comes out. Also, for anyone that use their computers for production or other mission critical purposes, we recommend you install this update on a test machine and try it out for a few days before installing it on your primary machine.

MacMedics also strongly recommends you have a tested and fully functional back up in place BEFORE you install any Apple system software update. Something could go wrong during the install, and you could have a major problem on your hands. Whenever Apple releases a major update to OS X we usually see 4 or 5 clients’ hard drives die that first day. If your hard drive is dying or already unhealthy, the extra hard drive activity needed to install a major update is often all it takes to kill a hard drive. Please see our web page [http://www.harddrivesdie.com] on the subject of hard drive failures.

Don’t forget that while Time Machine is an excellent automatic back up (just the way we like it here at MacMedics!), it IS very hard to test the RESTORE capabilities of such a back up. Read my post on Time Machine here. The short story is while you might not lose any data, you could be in for a major situation and delay if you want to recreate your hard drive as it was. The ideal situation is to have TWO back ups. One Time Machine and one “bootable” clone back up of your hard drive. That way no matter what happens you can boot off the clone and get right back to work.

We’ll post new info on our update warnings page and here in our Blog as it becomes available. We will also Twitter about anything you need to know in the meantime.

http://www.macmedics.com/updates.htm
http://www.twitter.com/macmedics