Unfortunately, grep decided that your system log was a binary file:
Scanning kernel log files for NVRM messages:
Binary file (standard input) matches
Please take a look in there and see if you see any NVRM error messages.
It's odd that your X server log stops right after loading libdri.so. I wonder if libdri could be doing something bad. It really shouldn't do anything, but you could try disabling it by adding
To the "Module" section in xorg.conf.