Why can the keyboard turn off?

Question

Keyboard

OS: windows 8.1
Keyboard normal ps / 2
The computer turns on normally, the keyboard works.
We open a site with a video, for example rutube, launch the video. The keyboard stops working, only the num lock is on, it does not respond to pressing + the video starts to stutter a little. After reboot everything works.
At the same time I open youtube, everything works as it worked.
What could be the reason?

Answer 1

It turns out that they added a memory bar, swapped the bars and everything worked.
ddr2 ps/2