1366x768 is a crazy resolution. What are you actually getting on your screen?
Post this much of your XF86Config-4 file
Code:
Section "Device"
Identifier "Generic Video Card"
Driver "vesa"
EndSection
Section "Monitor"
Identifier "Generic Monitor"
HorizSync 30-60
VertRefresh 50-75
Option "DPMS"
EndSection
Section "Screen"
Identifier "Default Screen"
Device "Generic Video Card"
Monitor "Generic Monitor"
DefaultDepth 24
.
.
.
SubSection "Display"
Depth 24
Modes "800x600" "640x480"
EndSubSection
EndSection