What version of PHP are you using? The minimum requirements are PHP 4.1, but there is an error in the current release of 1.1.0 that relies on PHP5, which will be fixed in a upcoming release.

I use PHP 5

This is a database access error.

Is this an existing or new installation? Was the admin/install.php script run before accessing the system? Is the rest of the error text avaiable?

It's a new installation (problem with the first bug)

No more error message, ou have the totality.

PS: i don't speak very well english, scuse me

J'ai du retirer une ligne dans core/database_api.php

if ( strtolower( $c_charset ) === 'utf-8' )
{//db_query( 'SET NAMES UTF8' );}

En effet cela provoque un erreur sur mon hébergement.

Which version of mySQL are you using? The requirements were upgraded to 4.1.1, but the version check was missed from the release.

I use mysql 5.?.?.?

After years of inactivity I am setting this issue to fixed, as this was reported to an old versions of MantisBT which is not longer supported.
Feel free to reopen the issue if there are still problems when using the latest stable version.