SOLUTION!!
Solution found at ArchWiki which i didnt know existed until today. It is indeed a problem with OSX 10.3 and QuickTime 7.1.5
This is how you can downgrade QuickTime 7.1.5 to version 7.1.3:
1. Download Quicktime 7.1.3 installer:
http://www.apple.com/support/downloads/quicktime713formac.html
2. Mount the installer package. This is very important.
3. Download and install Pacifist from this location:
http://www.charlessoft.com/
4. Run Pacifist. In its dialog press the "Open Package" button. Browse for the .PKG file in the mounted package. In the appearing list Right Click on the .PKG and from the context menu choose "Install To Default Location". Please note that if you mistakenly select the unmounted .DMG file into Pacifist instead of the PKG, there will be an installation but without an effect.
5. Check in the "User Administrator Privileges" checkbox. Press Install.
6. When asked tell the installer to replace the already existing files. Do this with all the files.
7. When the install process is finished restart the computer.
8. Run the QuickTime 7.1.3 installer package again WITHOUT Pacifist and let it install the files again.
9. Restart the computer
Works Perfect!!!