Recently, I browsed to a website, which appeared to consume all the computer's resources. Although the mouse cursor continued to move, the browser (and other applications) slowed down fast and soon stopped responding to commands. The screen did some odd things - coloured boxes of pixels where I would normally see text, etc. After a short time, the machine rebooted itself.
I was able to repeat the same behaviour with more than one browser, and more than one window manager (it is running under linux). Note that I visited the url but did not explicitly download any files, etc.
I checked the logs after a reboot, and it shows that the X server suffered a segmentation fault.
If that had happened in everyday application use, I would just assume that the application had a bug. However, because a website was clearly the catalyst, I wondered whether malware may be involved.
It seems plausible to me that malware has nothing to do with it. A quick web search indicates that a segmentation fault on X is a problem that has occurred before, and is broadly consistent with the other things I saw. (How a website could cause that, I don't know, but it does look like the simplest explanation.)
But I realise that if malware is the cause, I wouldn't know the difference. Is there any sensible way to corroborate that this was not caused by malware?
I realise that in theory that could never be ruled out entirely.