I could not easily figure out why you could only copy the shortcuts, and not the actual files, from the CD.
After some long reflections, I believe one reason might be that the CD is an audio CD, which do not contain any mp3 files. If the CD is indeed an audio CD, then the files on the CD would be something like Track01.cda, Track02.cda, etc. cda is shortform for "CD Audio". These cda files on the CD ARE 1 kb in size, just like the Windows Explorer shortcuts. When you copy from the CD to the computer or SD card, then the 1 kb files get copied. They are NOT playable by any mp3 players, including pTunes.
This might explain why you could not play the copied files on your computer either.
If the CD contains mp3, then the files would have names ending with .mp3
Are you sure the files on the CD are mp3 and not cda files ?
If your computer (I assume a Windows computer) is set to [Hide extensions for known file types], then you would NOT be able to easily tell whether a file is an mp3 or a cda file. Normally, by default, a Windows computer come configured with [Hide extensions for known file types].
If the files on the CD are indeed cda files, then you would need to convert the audio files into mp3 format using a CD ripper program, before you can use it for your PDA. On my computer I have Windows Media Player 10, and it has the Rip function, and can rip to mp3 format as well.
With regards to your PDA not able to play your computer's sample mp3 files which you had put onto the SD card, it would NOT be able to do so if your PocketTunes version is 3.1.1 and the "mp3" files are not mp3 but wma (Windows Media Audio) files.
I checked my computer' Sample Music folder, and found that the files there are wma files, and not mp3 files...