Have you experienced copying system files, reboot and nothing happen? Unable to replace system files?
One major problem is you did not mount system folder to Read and Write!
After running Root Explorer and inside the system folder. Remember to click on the MOUNT R/W.
If you do not mount it to Read/Write you will not be able to copy new files.
Make sure Root Explorer allow in SuperUser! If not, you will not be able to access system files will full right.
REBOOT! New system file will only executed after reboot.
Make sure you rename existing system file to BAK before copying new file! Else you might end up asking around for original file :)