Could you let us know what you get when you run the "Verify Integrity" diagnosis and repair function. That's here:

Open Firefox's Troubleshooting Information page using any of these methods:

• "3-bar" menu button > Help > More Troubleshooting Information
• (menu bar) Help > More Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Near the bottom, there is a section titled Places Database -- that's the file which stores history and bookmarks. Click the button labeled Verify Integrity. There may be a 10-15 second delay before results appear.

If all is well, the report that appears below the button should start with:

> Task: checkIntegrity
+ The places.sqlite database is sane
+ The favicons.sqlite database is sane
> Task: invalidateCaches
+ The caches have been invalidated
> Task: checkCoherence
+ The database is coherent

Does yours say that, or something else? You can select and copy the report, and then paste it into a reply for review and comment.

Note: in severe cases, you may need to rebuild one or both of the database files used for bookmarks and history. The following article has more information:

Fix "The bookmarks and history system will not be functional" error message

Thank you for your anwser.

I have done what you tell me to do and the result is :

> Task: checkIntegrity - Unable to fix corruption, places.sqlite will be replaced on next startup > Task: invalidateCaches - The task queue was cleared by an error in another task. > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: originFrecencyStats - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.

Please explain to me, if you can, what this means...

This line

> Unable to fix corruption, places.sqlite will be replaced on next startup

indicates that there was an unfixable problem with the main bookmark/history database. At the next Firefox startup, that file is going to be renamed to something like places.sqlite-corrupt and a new one will be created and populated from the last automatic bookmark backup.

Thank you...

I don't know if it's helpul because this problem has existed for several days and my Firefox has been restarted several times without anything changing...

I'm just reporting what that page says is going to happen.

Anyway, tank's very much for your help. Il will look for that tomorow morning then here, in France it's 20:32 PM.

Have a good day !