Here is the latest firmware revision from the Lite-On firmware download page for the 48x 12x 48x (LTR-48125W) CD-R/RW internal drive.
Download the file which must be run under Windows only, not DOS. After clicking the button to start the flash, it will almost immediately show 100% complete, but BE PATIENT. It takes another approximately 45 seconds to a minute before it actually completes the firmware flash and comes back with a dialog box stating that the firmware flash was a success and that you need to restart your computer.
Restart your computer and thats it. You will then be at the latest firmware revision R48VS0D which is dated 05/16/2003 and was posted to "Strengthen the stability of the "OVERBURN" function".
Here's the url for the firmware page at liteon.com.tw:
Lite-On firmware upgrade page
Hope that helps! :^)