回复：回复：回复：回复：俺把图贴在这里了。多谢！！ (图)

Hi thanks a lot for your help.
Yeah, these screenshots were taken when I was having such a problem. It's a home PC. And this is a relatively new problem, started from two days ago.
I haven't changed any setting; that's why I suspect (and fear) it might be a hardware problem.