Application preventing an unmount?

[Guest]

I am trying to install The Sims 2 on my computer. Now, with this installation, there is more than one disc involved. When the first disc is installed, it tells me to insert the 2nd disc. When I try to open my computer tray, a warning pops up on the screen saying, "Cannot Unmount Volume: An application is preventing the volume 'Sims2_1' from being unmounted." What should I do, if there is any way, to get my software completely installed?

[Twitchster1092]

Sorry, I am the one that posted this, I just forgot to login. Please direct your answers to me. Thanks so much.