read some guide on how to operate dosbox ?

Read my 60 Seconds Guide to DOSBox (and don't just read it - follow it too).

Since you are using disc-images, use the imgmount-command instead of the ordinary mount-command when mounting the CD-ROM.

If that doesn't help, come back with details on how you mounted your C and D drives, how you did the install, how you configured sound, music etc.

Reading the aptly named README file will be a good idea too.

Agh, I just found out my problem lies within the ISO I made. It says it's a CSS encrypted file, and that means it appears as an audio disc, which is worthless to me. If I ever get another copy of the game, this thread'll come in handy, I guess.

I've got a mounted disk image, not an actual disk, since I accidentally backed up the files on the disk when I switched computers.

You're not saying you destroyed the original data on a CD-ROM by overwriting it with other data, are you?

It says it's a CSS encrypted file, and that means it appears as an audio disc, which is worthless to me.

Are you talking about this CSS? If you are, then your post is even more mysterious than it looks at first glance. Either there's something really strange going on in your machine (like Gremlins forcing a copy protection/DRM scheme that works for Video DVD only unto your poor CD's or CD images), or you have a broken image. Just recreate the ISO image from your original CD, which i hope you do have.

Nope, I don't have the disc anymore.

And yeah, I'm as confused as you are about the CSS thing. Maybe I botched the whole ripping process or something.