In a on its support site, Apple confirmed that the update may hang during the installation process. "When attempting to update software using Software Update in , the update process may stop responding while 'Configuring installation' is visible in the update window," said Apple.

Mac OS X 10.5.6, which included nearly 40 improvements and application fixes, was . Prominent among the changes was one that increased the frequency of background synchronization between Macs and online service.

Apple pinned responsibility for the glitch on updates that were "only partially downloaded," but offered no other explanation, including whether the fault was on its end, in the update tool or due to user action.

The company told users to delete the partial download -- the files can be found in the "/Library/Updates" folder, said Apple -- and then re-run Software Update to download again and attempt to install it.

Users started reporting troubles as soon as Apple issued the update. "When I attempted to install, the process hangs on 'configuring setup'," said "davald" in a message posted to . "My [ ], after 15 minutes, is still in that mode. I did a forced restart, which returned me to 10.5.5."