strange problem!!!

When I start to use my system I open dolphin and press my left mouse button on a pdf file it opens okular and I view it.
BUT when the time passes I do the same but nothing happens!!!
AFTER a while doing the same I get “kdeinit could not launch …” message.

Same problem happens in midnight commander which returns that DISPLAY :0 is not found !!!

If I restart xdm.service its fine again!

Everything is updated to the last version!

Could this be a VIRUS or something is bad with KDE or Plasma or Firefox?

Doubt it

Try a different user and see if the problem continues there.

I blame Firefox for this behavior, I see a lot of memory occupied and not cleared.
Firefox starts with 1G and when the problem arose had 4G!!!
Many tabs where opened and closed but the total number of tabs were the same!