According to 9to5Mac the update has caused issues for owners of the new 13-inch MacBook Air when attempting to run iTunes 10.2.1.
The originator of a thread entitled '10.6.7 Freezes when attempting to run iTunes 10.2.1' on the Apple Discussions forum outlined the issue.
"Every time I run iTunes 10.2.1 I get as far as the window displaying correctly then within 20secs the machine freezes and is unresponsive to anything other than a forced shutdown via the power button. I have fixed disk permissions with the same result."
Several subsequent responders claim to have encountered the same issue. "I am having the exact same issue. I am running a new 13" MacBook Air - 2.13 GHz, 4GB RAM, 256 GB Flash Drive. Same issue with iTunes. It worked perfectly before the update - now with OS 10.6.7, the whole system freezes up when I open iTunes. Only solution is to power down and back up."
Apple has not officially responded to the thread, though other forum members have suggested some temporary fixes for the problem.
"There is a very simple fix. Power up and do NOT run iTunes. Then perform a complete shut down. (Apple menu & Shut down) -Then power back up. The problem with iTunes is gone, at least for now," one forum member wrote.
However, given the number of reports of the issue, it is likely that Apple will release a fix in the near future.