After I have used pd-vanilla on my Linux Mint computer and try to close it by clicking on the cross in the upper right corner it just refuses to stop. Also I can no longer watch video's on You Tube because they will not start. But I cannot open another patch to work with pd either! I have to restart my computer to get everything back to normal. What am I doing wrong?

I've had issues with PD and its sound server on Linux - sometimes I'll need to kill PD with some other method (like XKILL... that's alt-F2, then type "xkill" + enter, then click the skull-and-crossbones on your PD window).
I am not at my computer, and I can't recall exactly what causes my PD to stay open (but non-functioning)... but I have, sometimes, had similar issues (though not consistently!). Anyway, temporarily, at least some other kill function can keep you from needing to reboot the whole system.

@ Load074

Thanks! I tried it, and that stops Pd. But it doesn't solve the YouTube problem.

What Pd says when it refuses to close is this:

"opened 0 MIDI input device(s) and 0 MIDI output device(s)."

@Nobody I am not sure I can help, but someone will.
Could you try, before trying to open the new patch, checking everything in the "Media" tab of the Pd window.
If it says something "Midi" is available but not selected, then try selecting input and output devices.
If something is selected then try selecting "none".

Try setting...... in "Media"..... "Audio settings"...... the "Delay (msecs)" to a high number like 80 or 100...... and try changing your audio driver selection in the 3rd box of the "Media" window.

Midi and audio are trying to run, even in an empty patch without audio (DSP) turned on.
Some kind of mismatch with Mint or the computer components in the "Media Settings" seems the most likely culprit to me.......... and could cause a hang.
David.

The strange thing is that in the Media-section it automatically switches back to OSS-MIDI where as far as I know I use ALSA and Jack. I have set it on ALSA-MIDI repeatedly but it keeps returning to OSS-MIDI.

Pd has now opened and closed a few times without a problem, except that the videos on YouTube no longer start. Still have to restart my computer for that.

@Nobody I am on Linux Mint with Pd set to Alsa Audio. When i have DSP on, Videos on Youtube won't play, if i turn DSP off, they play.

@ ingox

Makes no difference by me, for as soon as I open Pd then YouTube stops. But I notised that on switching on DPS Pd gives the following message:
"ALSA input error (snd_pcm_open): Device or resource busy
ALSA output error (snd_pcm_open): Device or resource busy"

Looks like switching DSP off helps after all, but that it also depends on what got hold of the audio-output first Pd or YouTube...

I think I found a solution:

The problem with closing Pd and viewing videos on YouTube disappears if I don't select "jack" in the Media-settings and leave the settings on their default values: ALSA (after loading a patch) and OSS-MIDI. After switching DSP off I can even watch videos without closing Pd first.

Thanks for the tips, they helped me find the solution.

(There might be a problem when I want to connect Pd to other programs by means of jack, but we will deal with that later.)