Sitemanager error

DELETE FROM sessions WHERE UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(mtime) > 7200
Deadlock found when trying to get lock; Try restarting transaction

Backtrace

/home/sitemanager/admin/lib/database.php 15 sm_error
/home/sitemanager/admin/lib/sessions.php 52 dbexec
/home/sitemanager/admin/lib/sessions.php 19 sm_session_gc

Notice: Undefined index: file in /home/sitemanager/admin/lib/functions.php on line 694
Notice: Undefined index: line in /home/sitemanager/admin/lib/functions.php on line 695
 sm_session_open
/home/sitemanager/admin/lib/std_index.php 34 session_start