This is the first time I heard about
MarBSD. Initially I thought you made a typo and meant
MirBSD 
I have no idea why X keeps adding entries to
/var/log/Xorg.0.log.. Maybe you could contact the MarBSD liveCD creator and report the issue to him.
Alternatively you could try the LiveCD of of our forum member
jggimi. Be aware that this CD is based in OpenBSD 5.0, while OpenBSD 5.2 is about to be released on November 1st.