Nec ND-6650A Read Error Fixed

I recently came across a reading problem of my nd 6650A dvd-rw drive.
My dvd is a Nec ND6650A and my laptop is Fujitsu Siemens Amilo M series.
My dvd-rw drive wasn't able to read a lot of dvds (both DVD-R and DVD+R).
I burned some dvds with importand to me data using nero burning software.
I also run data verification for every disc and all finished successfuly.
After that my ND6650A couldn't read them. Isn't that weird?
I though that maybe a firmware update would solve the problem so I searched the net for firmware update.
Neither Nec official site nor FujitsuSiemens site had any update.
After a little search I went to Liggy's and Dee's NEC 6650 firmware site.
From this great site, for me, I downloaded and tried enough original versions but none of them solved the problem.
I decided that I should buy a new one and I started looking around.
But the next day I though "Why I don't try to flash again with some more firmwares? What do I have to loose? Drive is not working anw..."
So I went again to Liggy's and Dee's site and I tried Liggy's 1.62 Bitsetting Firmware RPC1.
For my surprise that modified firmware solved the problem.
Now my drive is working as it was before and it's region free too!
Thank you a lot Liggy and Dee. You saved me from buying a new dvd rw drive.