090226 9:16:08 - mysqld got exception 0xc0000005 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. key_buffer_size=1048576 read_buffer_size=1048576 max_used_connections=0 max_connections=60 threads_connected=0 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections = 123904 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. thd=000000003517E380 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... 0000000000000000 mysqld.exe!??? 00000000004D0602 mysqld.exe!Item_func_date_format::eq()[item_timefunc.cc:1775] 00000000005BD950 mysqld.exe!remove_eq_conds()[sql_select.cc:8772] 00000000005C00E6 mysqld.exe!optimize_cond()[sql_select.cc:8614] 00000000005C0661 mysqld.exe!JOIN::optimize()[sql_select.cc:818] 00000000005C3E37 mysqld.exe!mysql_select()[sql_select.cc:2285] 00000000005C4428 mysqld.exe!handle_select()[sql_select.cc:257] 000000000058D035 mysqld.exe!mysql_execute_command()[sql_parse.cc:3281] 000000000059398C mysqld.exe!mysql_parse()[sql_parse.cc:6322] 00000000004E4FD2 mysqld.exe!Query_log_event::exec_event()[log_event.cc:2070] 0000000000521E33 mysqld.exe!exec_relay_log_event()[slave.cc:3427] 00000000005224F5 mysqld.exe!handle_slave_sql()[slave.cc:4030] 0000000000677CF9 mysqld.exe!pthread_start()[my_winthread.c:85] 00000000007BAC77 mysqld.exe!_callthreadstart()[thread.c:295] 00000000007BAD45 mysqld.exe!_threadstart()[thread.c:275] 0000000077D6B6DA kernel32.dll!BaseThreadStart() Trying to get some variables. Some pointers may be invalid and cause the dump to abort... thd->query at 000000000116AC6C=CREATE TEMPORARY TABLE IF NOT EXISTS test.daily_avg_level (Station INT(5) NOT NULL,DATSa DATE NOT NULL,DailyAvgLevel FLOAT NOT NULL,PRIMARY KEY (Station,DATSa)) ENGINE MEMORY SELECT Station,DATE_FORMAT(Dat,'%Y-%m-%d') AS DATSa,ROUND(AVG(auto_hydro_1h.Stoej),0) AS DailyAvgLevel from auto_hydro_1h WHERE date_format(Dat,'%Y-%m-%d')= NAME_CONST('DATS',_binary'2009-02-23' COLLATE 'binary') GROUP BY Station,DATSa thd->thread_id=2 The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains information that should help you find out what is causing the crash