Well, I have had a lot to do today, but I took a look at your files finally, and while I can not be 100% in my diagnosis, I hope that this will suffice.
I noticed in your Xorg that the kernel and X WTF's trying to figure out your display resolution. We can tell X what your resolution is; via the file located at '/etc/X11/Xorg.conf'.
Append this somewhere in the file (doesn't really matter too much), with your correct resolution. If the display option is already there append it under the 24 header.
(Quoting the Arch Linux Wiki
Add desired Modes to the "Display" subsection, at least under the Depth 24 header, e.g.:
Viewport 0 0
Modes "1024x768" "800x600" "640x480" # put your desired resolution here.
The kernel also just did an FSCK of the FS, and repaired a few things. Perhaps this may have cause problems.
-fs (dm-1): INFO: recovery required on readonly filesystem
EXT4-fs (dm-1): write access will be enabled during recovery
EXT4-fs (dm-1): barriers enabled
kjournald2 starting: pid 395, dev dm-1:8, commit interval 5 seconds
EXT4-fs (dm-1): delayed allocation enabled
EXT4-fs: file extents enabled
EXT4-fs: mballoc enabled
EXT4-fs (dm-1): orphan cleanup on readonly fs
EXT4-fs (dm-1): ext4_orphan_cleanup: deleting unreferenced inode 23102
EXT4-fs (dm-1): ext4_orphan_cleanup: deleting unreferenced inode 22924
EXT4-fs (dm-1): ext4_orphan_cleanup: deleting unreferenced inode 22925
EXT4-fs (dm-1): ext4_orphan_cleanup: deleting unreferenced inode 12183
EXT4-fs (dm-1): ext4_orphan_cleanup: deleting unreferenced inode 5260
EXT4-fs (dm-1): 5 orphan inodes deleted
EXT4-fs (dm-1): recovery complete
EXT4-fs (dm-1): mounted filesystem with ordered data mode
I noticed you have a Toshiba laptop. There is an LQ thread about these and, wham!, your dmesg says it all:
[Firmware Bug]: ACPI: ACPI brightness control misses _BQC function
Perhaps does this system instability happen when you change the brightness? We can turn ACPI off, but only if you don't care about your fan never going, power saving features, and perhaps battery problems. (I don't think you'll want this...)
Another thing, the kernel makes quite some fuss about APIC. This is a fairly major function, but I did some Googling and looked at your dmesg and realized the kernel only sees 1 processor. Perhaps we can fix some problems by appending the "noapic" kernel parameter to you grub.conf (GRUB2), or menu.lst (GRUB '1'). This may well be safe enough to do w/out really doing too much because you only have 1 CPU. (or so Linux says...)
Quoting the kernel
WARNING: at arch/x86/kernel/apic/apic.c:247 native_apic_write_dummy+0x32/0x3e() (Not tainted)
Brought up 1 CPUs
Total of 1 processors activated (4388.63 BogoMIPS).
Another case is that you have two CPUS, but your BIOS is messing stuff up. The kernel reported:
Local APIC disabled by BIOS -- you can enable it with "lapic"
You could enable the parameter, the same way as above for disabling it, but instead appending "lapic"
It looks to me like the Linux kernel is having a lot of trouble with APIC. The laptop also has a firmware bug with brightness. Try the suggestions above, and have a look at the Toshiba's BIOS and see where APIC is disables\d, or if it has the parameter. I believe this will solve your problem
Remember that the Kernel often will say what the problem is.
I hope this information resolves your issue.