A day after the software was released via Apple's download service, users flooded the company's online support forum with hundreds of complaints about the upgrade. Most centered around OS freezes and so-called "Blue Screens of Death."
"The latest version of Leopard (10.5.6) downloaded automatically via Software Update. However, when I attempted to install, the process hangs on 'configuring setup,'" wrote a user logged in under the name Davald.
"I have owned dozens of Apple computers since my first purchase in 1977, and I also have the OS X 10.5.6 update problem," reported a user named Jim Needham.
User 'Dr. Nick' said, "Have to add that my iMac is playing up. Upgraded, and can't get past the screen where you type your password, the screen goes blue, and it cycles through a slightly different shade of blue to take me to the login screen again."
Another, going by the online handle Xapplimatic, said his problems weren't limited to a single machine. "All 7 of my Macs (Intel & PPC) are all hung on the installation. None of them have gotten past "configuring installation" and it's been over an hour... I'm really worried," he wrote.
Others reported that installation of the update caused problems with Bluetooth connections, the Safari Web browser, sound settings, energy-saving settings, and a host of other Mac features.
Apple on Monday cautioned users to proceed cautiously with the update. "You may experience unexpected results if you have third-party system software modifications installed, or if you have modified the operating system through other means," Apple said in a note on its Web site.
Users could also have trouble "if you have moved applications from their default locations," Apple said. The free download for existing Leopard users was supposed to offer a wealth of performance, convenience, and security updates.
iChat users supposedly will see fixes for an issue that causes an encryption alert to appear in the chat window and for a glitch where users that set their status to "invisible" are automatically logged out of iChat.
For gamers, the update includes modifications designed to improve performance of a number of games and fix image distortions that occur with some ATI graphics cards.
Mail users should see a fix for a problem that causes messages identified as junk to remain in the inbox, while Mobile Me fans are supposed to get faster synching for contacts, calendars, and bookmark lists.
Graphics pros will get improved performance with Adobe's C3 application suite, according to Apple. Mac OS X 10.5.6 is, among other things, also designed to improve performance and fix bugs in Apple's Time Machine archiving system, Safari Web browser, DVD Player, and TrackPad portable input system.
Apple on its Web site has published a full list of the issues that the update is designed to address.
Apple debuted OS X 10.5, or Leopard, last year. Its slick interface, along with some business-friendly security features, have helped Apple make inroads against Microsoft Windows in consumer and business computing markets.