Nec 4551a Read Problems

I have a NEC 4551A WITH FIRMWARE 1-07. As a burner it's fine! Either cd or dvd. Low errors and playable to every device pc or standalone. And believe me I burn a lot disks and give to friends, mainly cd but dvd enough also.
The problem is on reading some disks. I get CRC errors. The strange thing is that it can open/read disks [cd/dvd] that are really bad and no other devices can read. But with some disks that are physically fine and not with much errors, acoording to other devices I have reading problems and get CRC errors. These can be read by other devices old and not in good condition that usually cannot open a disk with errors. I'M talking of some friends drives and mainly for my second drive an old read only MSI ATAPI 16. This MSI drive sucks... I use the emergency hole to open the tray. This bad old drive even with fine cd/dvd needs time to read. However even slow, IT can read 90% the disks that the NEC 4551A cannot.

AS i told I'm satisfied from the NEC as a burner but if I flash a new firmware is it possible to solve the reading problems???

Flashing with a different base firmware may improve reading performance, flashing with a modified firmware won't improve reading performance, as reading strategies are not modified, except in the case of some drives where riplock is removed.