'Cause that's what he's saying happened.
Rarely can you be so certain that what a person's saying is fact. There is an auto select feature in Cubase that will automatically record enable channels when selected. This doesn't over-ride recording.
While I'm sure he is honest in his belief in the facts as described; I don't think this is a known bug. Sometimes, as tough as it may be to admit, user error is the better explaination.
I use 4.03 in my studio everyday for 8 hrs at a time. No such problem. Check the settings and then call Steinberg if you need tech support.
This is not a known "bug." ftp://ftp.steinberg.net/Download/Cub...tfix_VH_IS.pdf
Link for all known bugs, fixes, and workarounds.