From the symptoms this sounds like a GPU lockup bug. Once it occurs, could you please grab the information listed on https://wiki.ubuntu.com/X/Troubleshooting/Freeze#Reporting_GPU_lockup_Bugs - you might need root privs to look in /sys/kernel/debug - and attach the information here? Thanks.
From the symptoms this sounds like a GPU lockup bug. Once it occurs, could you please grab the information listed on https:/ /wiki.ubuntu. com/X/Troublesh ooting/ Freeze# Reporting_ GPU_lockup_ Bugs - you might need root privs to look in /sys/kernel/debug - and attach the information here? Thanks.