Another odd Mozilla problem

[Sivar]

For some reason, I cannot run both Mozilla Main and the Mozilla browser at the same time. Once I try to run the second after running the first, I get a window:
"Select user profile"
and have buttons to create/rename/delete the profile. One profile, "Default" exists. If I select that profile and click the "Start Mozilla" button, I get:
"Mozilla cannot use the profile "default" because it is in use.

Please choose another profile or create a new one."

Creating a new profile would involve essentially setting up all of the Mozilla stuff from scratch. What's going on?
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The greatest deeds are still undone, the greatest songs are still unsung...

[delta407]

Mozilla puts a lockfile on your profile (.mozilla/profiles/default/lock, IIRC); the bottom line comes down to don't fire up multiple instances of Mozilla. Just Ctrl-N