It is possible that (anti-virus) security software is causing the problem. Try to disable security software temporarily to see if that makes a difference.

Boot the computer in Windows Safe Mode with network support to see if that has effect.

• https://www.bleepingcomputer.com/tuto.../how-to-start-windows-in-safe-mode/
• https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/

Thank you. After restarting firefox, it seems to have resolved the issue. For the time being, I would like to wait and see and use the information you gave me so that I can use it in the event of a recurrence. Thank you for your cooperation.