Comment 7 for bug 831336

@Thomas, it does sound like a compiz bug, however "CompositorRunning: None" indicates no compiz. (I thought that would detect gnome-shell/mutter too but perhaps not). In any case, GdmLog2.txt shows:

*** glibc detected *** /usr/bin/Xorg: free(): corrupted unsorted chunks: 0x0000000002b844c0 ***
======= Backtrace: =========

Which is why I asked about lightdm vs. gdm. That log shows a 8/12 build date on xserver, which seems to correspond with the timeframe of 2 weeks. So, while xterm might be triggering it, it's looking more like an xserver bug to me.