CD-ROMs can be particularly problematic, because the
old way of using them generally involved "faking SCSI." Now, most IDE CD-ROMs can be supported directly, as the IDE devices that they really are. (The old magic involved a strange kernel-parameter which is also no longer required.)
This might require some adjustment to,
e.g. /etc/fstab entries.
I just stuck a disk into the drive (lots of drives won't get too far if they're empty) and fiddled with
mount.
I also did
dmesg | grep hd[a-d] to get an idea of what messages might appear that involved the CD-ROM device. Mine turned out to be
/dev/hdc.
It's definitely true that "2.6 is different, sometimes
subtly different," and when "something doesn't work that used to work before" (inevitably, of course), one tends to "panic

and reboot" just to get back to normalcy. But the actual problem and its solution

might prove to be simpler. And you basically need to
be in the 2.6-kernel in order to fully
diagnose what's not-quite-right.
If, in the
dmesg output, the kernel can
see the device, then "it's probably
not a kernel-problem." That narrows your range of possibilities right there.
Also, device-handling in 2.6 is
considerably different than it was before. Those "thousands of unused entries in
/dev" are
finally going away for good.