I have a LiteOn 40-12-48 and it has a bloody-annoying habit:
If you place a CDRW or CDR disk in the drive which is certified to anything less than the drive's max-speed rating, Nero (or the firmware, I'm not sure which is to blame) only shows that the drive will write to maximum of the disk speed.
Example:
The drive is capable of writing to CDR at (this is only off the top of my head, so don't take it literally):
40x, 32x, 24x, 16x, 8x, 4x
Now, say you place a 16x-rated CDR in the drive. Of course, it will only write at a max of 16x, but the bit that is so annoying is that if you tell Nero to burn again, but put a better CDR disk in, say, one rated at 40x, Nero will still pretend that the LiteOn drive will only write to a maximum speed of 16x!! The way around this is to insert the new 40x CDR disk **BEFORE** you even tell Nero you are going to burn the project - i.e. BEFORE Nero jumps to the smaller burning dialogue box.
It took me half an hour to work this out when I first bought my drive - to begin with, I thought I'd been sold a flashed fake!
I realise you were referring to CDRW, and I must admit I steer clear of RWs, unless they are DVD-RWs, but I hope this still helps.
CDrZeus