'glxinfo' Problem

[das]

'glxinfo | direct'

Or, even

'glxinfo' 

are leading to a simple gdm restart, where you have to log-in once
again. 

Has the same problem occurred to anyone else?

My vga driver is 'sis' (after editing 'xorg.conf', the system detected
one was 'vesa' that led to substandard vga) and the 'lspci' vga line is:

01:00.0 VGA compatible controller: Silicon Integrated Systems [SiS]
661/741/760 PCI/AGP or 662/761Gx PCIE VGA Display Adapter

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das