Xserver is video/graphics.
You need to provide more information for someone to help you.
You may start with posting the Video card section from the following file:
/etc/X11/xorg.conf
You will see a section similar to the one posted below, probably near the bottom of the file.
Code:
Section "Device"
Identifier "NVIDIA Corporation NV17 [GeForce4 420 Mac 32M/GeForce 440 Go 64M]"
Driver "nvidia"
EndSection
Section "Screen"
Identifier "Default Screen"
Device "NVIDIA Corporation NV17 [GeForce4 420 Mac 32M/GeForce 440 Go 64M]"
Monitor "Generic Monitor"
DefaultDepth 24
Option "AllowGLXWithComposite" "True"
Option "AddARGBGLXVisuals" "True"
SubSection "Display"
Depth 1
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x800"
EndSubSection
EndSection
You will probably need to press Ctrl-Alt-F1 and log into console and logon. You can then run the command vim /etc/X11/xorg.conf in order to get into this file and edit or view the file. (You will need to run sudo vim /etc/X11/xorg.conf to edit this file.)
Some common fixes would be:
1. Change the driver to a default (ie...if you have an Nvidia card the open source one would be utilized by changing the text to "nv") If you have another model you'll have to search around as I am only familiar with Nvidia
2. Change the DefaultDepth value to a lower value, maybe 16 if it's higher than that now.
3. Change the Modes section to a lower resolution and test. Maybe 1024x768 and see if that helps. (The modes would be changed based upon the DefaultDepth you specified above.)
I have fixed almost all my Xorg problems making these changes. I hope this helps.