diff -Naur mantisbt-1.2.3/api/soap/mc_file_api.php mantisbt-patch/api/soap/mc_file_api.php
--- mantisbt-1.2.3/api/soap/mc_file_api.php	2010-11-18 15:53:59.000000000 +0100
+++ mantisbt-patch/api/soap/mc_file_api.php	2010-11-18 15:56:40.000000000 +0100
@@ -175,9 +175,10 @@
 		$t_project_id = $row['project_id'];
 	} else if ( $p_type == 'bug' ) {
 		$t_bug_id = $row['bug_id'];
+		$t_project_id = bug_get_field( $t_bug_id, 'project_id' );
 	}
 
-	$t_diskfile = $row['diskfile'];
+	$t_diskfile = file_normalize_attachment_path( $row['diskfile'], $t_project_id );
 	$t_content = $row['content'];
 
 	# Check access rights