I had the same problem of can't erase the disc.
Exactly same as described above, only nero could erase the disc. imgburn/cdburnerxp/deepburner all failed to erase, and uncheck the "proper write to +RW" solve the problem, but disc erase with this option can't be used by other software like cdburnerxp...
MB : asus p5b
Drive: Pioneer 112D
Media memrex: dvd+rw x4
OS: windows XP
After reading this thread, I went to Asus website and install two drivers (one for JMicron controller and one for Intel chipset), I am not sure which one take the effect, but it works now!
Thanks for creating this software and provide support!