Hm... can you paste the contents of the file /var/log/XFree86.0.log here?
When booting into Linux you should be able to issue some boot/kernel parameters before the actual boot-process is initiated. Every Linux-distribution offers such functionality. Take a look at your distributions manuals on how to do that and either make sure you boot up in "single-user" mode or with init-level 3 (this would be better/more convienent than "single-user").
Once you got this done you should easily be able to "cat /var/log/XFree86.0.log")