Problems with disc swapping

Recently I read about this disc swapping trick and decided to test it with a game that was never released where I live: Shining Force 3 Scenario 1

After a few tries I got the timing right and it worked, but I still have a few problems:

First, an error message appear on the top of the tv screen:

Cd read error!

Please check cd and pickup lens.

Although the message does appear, the game continues to play and sometimes the message goes off (although it shows up again later)

Also, the game sometimes freezes when changing screens, like in the loading times... I can still hear the music, but the screen just goes black and that's all.

I'd like to know if that errors are from my Saturn, from a bad cd or from a bad disc swapping.

To start off with... If Scenario 1 wasn't released in your region... then you must live in the north pole
Scenario1 was released in japan, usa, europe and all over the place...

Now, about that error, i'm almost sure it is a problem in the image you've downloaded...

That message appears in a scenario3 image that was on ftp's sometime ago..

The reason was that some files on the cd couldn't be read due to a bad rip...
Funny, I tried to do the cdrw reading adaptation and although I have some problems with games burned in cdrw, I now don't have problems with the cdr I recorded Shining Force 3 (I have a modchip and it could read others non-official games, but I had problems with this cdr).

Oh, BTW, I live in Brazil and I'm pretty sure Shining Force 3 wasn't released here