The sound of halionone and vst is unstable

With cubase 5.3 that I just reinstalled for the third time completely because halionone sounds were turned off, it’s still the same problem: I open a Halionone track, I choose my instrument and there I have 3 options: the sound of the instrument is correct, I start to play it then the sound disappears; and there, impossible to recharge it. Or the sound is recharged but almost inaudible— We say nice, I have time today to work on my composition and we spend the day scratching our heads in front of the screen.
If anyone has any idea where the problem might come from, thank you in advance.

Hi and welcome to the forum,

The latest Cubase 5 update was Cubase 5.5.3. Make sure, you have the latest version installed, please.

Try to increase your Audio Device’s Buffer Size, please.