how to debug crashing X-app

[Peter Boosten]

Hi all,

I'm having trouble with my local X server, I think:

If I start nethack(-qt), it throws me out of my X session, right back to 
  the xdm login prompt. If I start nethack from another machine (on the 
same X server) the same happens. If I use another X server, for instance 
xming (on Windows), nethack runs normally, so I think it's (some part 
of) X server.

But which part could that be? How can I analyse what exactly is going on?

The Xorg.0.log.old shows these messages on the end, but googling shows 
nothing meaningful.

Fatal server error:
Caught signal 11.  Server aborting

(==) VESA(0): Write-combining range (0x0,0x1000) was already clear
(==) VESA(0): Write-combining range (0x0,0x1000) was already clear
(==) VESA(0): Write-combining range (0x0,0x1000) was already clear
(==) VESA(0): Write-combining range (0x0,0x1000) was already clear

TIA

Peter
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