Back when we were Windows PC users, there was a standard protocol to be followed after adding or updating software to the computer: run Norton Disk Doctor. Or SystemWorks. Or some other third-party program capable of fixing all the damage that was accidentally or thoughtlessly done to the computer’s registry by an installer when something new was added. It was a mess, a pain, and one of many things we were thrilled to be without when we switched to Macs. We were even more impressed when we saw our Macs taking an extra minute or so after certain installations to optimize the hard disk: that one minute delay reduced countless potential future slowdowns.

But in recent months, post-installation blues with Apple software have created problems for our Macs, too. We didn’t write about the last one, the screwy Mac OS 10.5.7 update, because we’re not a Mac OS-focused site. For that one, two iLounge editors saw their aluminum MacBooks stuck in blue screen loops after trying to upgrade from 10.5.6 using Software Update. Ugh—it was a throwback to the Microsoft days. But the latest one is iTunes 8.2, QuickTime, and Front Row-related: install them and you may notice that your Mac’s running slower, its fans are constantly spinning, and its battery is draining faster than it did before.

To be completely fair, this isn’t the first time that iTunes, QuickTime, or other Apple software has done this sort of thing, but the problem has become a fairly serious one: why should users have to suffer for days, weeks, or longer with lower battery life and hotter machines after installing all but mandatory updates to core applications? Thankfully, there’s a fix, a solution that is free, easy to use, and will almost certainly improve your Mac’s performance. It’s called Disk Utility, and it’s hidden in the Utilities folder on your Mac—a folder that’s tucked into your Applications folder.

You can find the program with Spotlight at the top right of your Mac’s screen, but we’d advise adding the Utilities folder to your list of Places (see screenshot) by going into your Applications folder, dragging the Utilities folder into the sidebar, and having it there for reference whenever you need it. [We also use the more powerful, free third-party application Onyx, which hasn’t been updated yet for 10.5.7.]

Disk Utility does a number of things, generally (but not always) quickly and well. Here, the only things you need to know are to select your hard drive from the list on the left of the window, and press the button called “Repair Disk Permissions.” This starts an invariably harmless process that goes through and fixes screwy file information on your Mac. After five minutes, it will most likely have found a bunch of Apple programs with messed up “permissions,” which it will fix instantly. Apple’s most recent iTunes and QuickTime updates led to over 60 permissions errors, all found and “repaired” by Disk Utility. Then you can restart your Mac, and you’ll most likely find that it’s running cooler, quieter, and faster.

But not always. When we ran Disk Utility a second time to take additional screenshots for this article, we were surprised to discover that some of the problems had persisted, and Disk Utility “repaired” them again. We’re not quite sure how or why that would be happening, but it did, and iTunes, QuickTime, and Front Row were all listed as being to blame. The same thing happened a third time, too. Amazingly, we’ve found ourselves back to where we were in the Windows and Norton days, running applications just to keep our Macs them running properly, and not always succeeding. Here’s hoping that Snow Leopard and the next iTunes release bring things back to the way they should be.