With any program being updated, there will be a few quirks at first while the new features get used in various people's setups and configurations. The same goes for iTunes 10, where people are finding a few oddities that seem to be feature changes or bugs that need to be ironed out.
iPhone 4 apps causing crashes
Some people have been experiencing crashes in iTunes 10 when connecting their iPhone 4 devices and selecting applications to transfer. If this happens, try resetting the iPhone and also try removing iTunes' preferences (called com.apple.iTunes.plist and stored in the /username/Library/Preferences/ folder). You can also try launching iTunes in Safe Mode by holding the Option-Command keys when launching iTunes.
Album lists no longer resize
Album artwork resizing in list views is no longer possible. The only way to have resizable artwork is to use the sidebar's album viewer window and then optionally click the artwork to open it in a dedicated window.
Though social networking is a popular Internet development that companies are eager to take advantage of, it is not for all of us and many people prefer to avoid it. You have the option to ignore Ping in the sidebar, and you can also remove it by disabling the iTunes Store (provided you do not purchase items through the Store).
To do this, go to the iTunes preferences and in the "Parental" section select "Disable iTunes Store."
AirPlay not working
A few people have reported the iTunes AirPlay feature is not working as it did in older versions of iTunes. For some their AirPort Express devices are selectable but no sound seems to be coming out of the unit.
If this happens, try setting the master volume in iTunes to its highest level, and do the same for your various wireless AirPort devices in iTunes. This can be done in the "Multiple Speakers" window (available from the "Window" menu). If your AirPort Express devices do not show up in iTunes, try unplugging them and shutting down your computer for a few minutes, then plug them in and start everything back up. Sometimes a quick reset like this is the easiest way to force-detect items and have them show up again.
"Nathan Volker" being followed in Ping
A few people have found the name "Nathan Volker" to be in their Ping profiles, and have wondered what is going on. Apparently this person created an account with the name "Steve Jobs" and then changed the name, resulting in some odd behavior. The account has been removed by Apple and should not affect anything. You should be able to stop following this account in Ping if you see it appear.