Did some searching on Google, and found others have had this same problem with your Lite-On 52x24x52x drive, here:

http://club.cdfreaks.com/archive/topic/69594.html

Short version is to disable Smartburn in Nero, or use media that's certified to work at higher speeds (I didn't know this, but apparently Nero checks the blank CD-R).

You can also find the older firmware here, if you wish to downgrade. Although maybe that's not such a good idea.

I've never had a problem with Nero. With Roxio, on the other hand, I had an older version of EZ CD Creator that I uninstalled, and it wiped out a very important Windows driver, leaving me unable to start Windows. Feh.