Problem with logging into the browser after frequently turning on the computer.

You could try to Repair Your Current Profile Database. Since this has already happened multiple times, your current profile might have lingering corruption. In Firefox, you could: - Click the three horizontal lines (menu) in the top right. - Go to Help > More Troubleshooting Information. - Scroll down to the Place Database section and click the Verify Integrity button.

This will scan, reindex, and repair your local storage files. Hope that helps!

Thanks. I checked the integrity. How pressing a single button could fix anything is unclear. I tested it for four days, and it seemed to stop logging out of the browser. But one problem persisted. When I launched a game from Steam, I minimized it, launched Firefox, and then went to YouTube. When I started watching any video, the screen immediately went blank, a message appeared on the monitor saying the device would go into standby mode in 5 seconds, and the fans in the system unit started screaming at full volume. I tested it in Chrome browsers, and this problem didn't occur.

When I frequently turn off my computer using the system unit's power button,

Do you mean the GUI power or the physical button.

What Linux are you using ?