Please also check /var/log/Xorg.*.log and, more importantly, ~/.xsession-errors for issues, and consider uploading them, too.
Also, please ensure you have deactivated any 3D desktop/window manager extensions while using MegaGlest.
This issue _may_ be related to your nvidia drivers and the twinview / xinerama setting, so please report also whether you are playing on your primary or secondary display, and see if it crashes on your primary display, too.
Have you successfully played other 3D games on your computer, yet?
Please note that while I'm trying to help it is very likely that this is an issue not related to MegaGlest, since so far you are the only one experiencing this. This is a good indication that it is not a bug in MegaGlest. But let us continue for now.