Microsoft Teams stuck after few seconds of conversation

Hi,

I just bought a new Desktop PC and I'm experiencing problems when doing class lessons with Microsoft Teams. Being the teacher, I need to share my screen, run audio sources, etc., but with this new PC I've bought my students can't see me after doing this. I tried both the .exe application and the browser version and I have the same problem. Until yesterday, with a very old computer, I did not have such problems. I tried to uninstall the McAfee Antivirus included in the computer but nothing happened.

Can somebody help me please?
Thank you in advance.

Veronica