Briefly, one way of "circumventing" the issue is simply to set your
Virtual setting to the same value as your
resolution - (ie your 1st Modes value) - for example: (from a screen section in /etc/X11/xorg.conf)
Code:
Subsection "Display"
Depth 16
Modes "800x600" "640x480" "1024x768"
ViewPort 0 0
Virtual 800 600
EndSubsection