Reader Bruce Hoffman reports losing the Join CD Tracks command after upgrading to iTunes 5. Although the command still appears in iTunes’ Advanced menu, it’s grayed out even though he’s done all the right things—inserted a CD and selected adjoining tracks.
Thankfully, this is one of those cases where iTunes is confused rather than broken. The solution is to toss iTunes’ preference file, found by following this path: youruserfolder/Library/Preferences/com.apple.iTunes.plist. Quit iTunes, move the aforementioned .plist file into the Trash, restart iTunes, and the command should work again.