100% CPU usage and black screen for over a minute when starting Cinnamon.

Distribution

debian-testing

Package version

6.0.4

Graphics hardware in use

GTX 1060

Frequency

Always

Bug description

On my home computer I have two Linux accounts: one for work and another for gaming. Both use Cinnamon. Both have been customized slightly.

There are no issues with the work account. Cinnamon starts up fast and works perfectly.

On the gaming account cinnamon starts with a black screen, hogs 100% of CPU and stays that way for a good minute or more. Then it starts working normally.

This started after I had to hard reset my computer after one game froze the PC.

I had the gaming account temporarily configured to use only one monitor (one game kept starting on the wrong monitor) and whenever I try to reconfigure it to use two, I get a black screen and the new configuration timeout countdown finishes before it ends, eventually reverting back to a single monitor layout.

How do I debug what's wrong and what's the best way to reset all Cinnamon settings on one account?

Steps to reproduce

I have no idea what went wrong.

Expected behavior

Not hang with a black screen and 100% CPU usage for over a minute when starting up.

Additional information

No response

The report names no source file, test, or entry point. Start by reproducing Cinnamon startup on the affected gaming account with the single-monitor configuration, then compare its settings and startup behavior with the working account; done means startup no longer produces the black screen or sustained 100% CPU.