Yep, you'll need to check your extensions folder. It's in the System folder.

Also, what OS are you using?

There's a control panel called "Extensions Manager" which can be used to determine which extns load at startup. You can create sets for different uses, and restart into each one. Someone before you may have created a set without the CD extensions in it.

There's another folder called "Extensions (disabled)", That's where the Manager parks the extns that won't be loaded at the next startup. If you don't see the CD extensions in the "Extensions" folder, check the disabled folder.

I highly recommend a little freeware app called InformINIT. It's a database of all known extensions, control panels, and other system files, up to a certain point in System /Mac OS history, with a thorough description of what each is for, and known clashes with each other.

I'd also recommend an alternative to the Apple provided Extensions Manager called Symbionts. I've heard Conflict Catcher is good too, but I've never used it. The Apple EM doesn't show or control all system startup files, just the ones Apple at the time thought you "needed" to know about.