Actually, I've fixed it already.
I'm not sure what I had done but it's fixed.
What happened and what I tried:
BSOD due to iTunes
Late at night so system reboot with monitor off
<Problem Started>
Reinstalling Driver
System Restore
GMod
Force Screen Resolution
Reinstall monitor driver
Edit registry(Setting every single 1600x900 value to 1440x900)
Restarted, didn't work
Tried editing again, late at night, didn't restart.
Turned Monitor Off
Morning BLACKOUT with monitor off.
Computer started with correct resolution...

So I now know that the problem is caused by turning on the system with the monitor off, but what fixed it?