I download and install software on my Mac on a regular basis. I have used every version of Mac OS X client since Apple released v10.0 in 2001. In doing so, I occasionally encounter quirks and unexpected behaviors that only affect a particular operating system.
A recent case involves Leopard (OS X 10.5), where I’ve encountered situations where a disk installer that I’ve used to install software won’t eject from the desktop or the Finder.
There are several ways to address the issue. One method is to reboot. Another is to Force Quit the Finder. My preferred method and one that I believe carries the least risk is to use Disk Utility to manually eject the disk image.