Created attachment 100209 [details] content of /sys/class/drm/card0/error It doesn't matter if hardware acceleration is enabled or not. I'm not sure if webgl capabilities are used by default.
This has to do with webGL. Only this website gives problems, otherwise the games and all work well.
Sorry no one ever investigated your bug. I do not have a Sandybridge GT1 to test, but everything seems to be working on kernel 4.9.5 and mesa-13.0.3. Please reopen if you can still reproduce with Mesa 17.0.
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