I just bought a 40125S (firmware ZS06) and I use it with Nero 184.108.40.206 and CD-Mate. When burning with Nero, sometimes the burner LED switches from red to yellow (I think that means re-calibrating speed) and Nero hangs (progress bar stops and application cannot be terminated). The burner never leaves the 'yellow'-state until I shutdown Windows 2000 (no ServicePack) or sometimes I even have to hard-reset the computer.
I don't use 40-speed certified media (only 24x), but I think SMART-Burn should handle that anyway. If I switch to a lower speed, I never saw this behaviour. Nor did CD-Mate ever hang when burning with 'max-speed'-setting (whatever that means).
Thanks in advance,