Apple’s Leopard OS apparently swallowed the wrong kind of medicine when it got Monday’s update. Cries of dismay have been heard from many users who encountered problems such as dead USB ports, Bluetooth connections breaking up on them and some sort of popping or bleeping noises during system restart.

The guilty party is the OS X 10.5.6 update. Of course, Apple intended it as a champion of improved usability, not as an agent of destruction. According to PCMAG, it was meant to improve a whole bunch of features, like gaming performance, synching between the iPhone and the address book, an encryption alert showing on the iChat window and, for Intel-based Macs, roaming capabilities of AirPort connections.

And that’s not all. This update should have solved the quitting from Mail problem, as well as the stuck junk mail issue, not to mention increasing the speed of MobileMe synching. The OS X 10.5.6 package was also intended to fix the bug that caused parentally-controlled accounts to access the iTunes Store; Web proxy servers in Safari should have fared better as well.

Unfortunately, it actually made things worse. Users report all kinds of problems caused by the update: Macs getting stuck on “configuring setup”, or for those who made it past installation, synch with Blouetooth down the drain, mouse recognition gone, failure to open Suitcase Version 2.0 or connecting to the AirPort wireless network.

Apple should come with a solution sometime soon. Until that happens, there are some ways to avoid these troubles (like removing update files), but there’s no sure recipe. Some few very lucky users actually have no problems at all.