090415  9:33:06 [Note] Starting crash recovery...
090415  9:33:06 [Note] Crash recovery finished.
090415  9:33:07 [Note] Event Scheduler: Loaded 0 events
090415  9:33:07 [Note] c:\dbs\5.1\bin\mysqld: ready for connections.
Version: '5.1.35-Win X64 revno: 2852-log'  socket: ''  port: 3510  Source distribution
090415  9:34:09 - 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=8384512
read_buffer_size=131072
max_used_connections=1
max_threads=151
threads_connected=1
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 338112 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

thd: 0x7893240
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...
00000001400E2E8C    mysqld.exe!SQL_SELECT::test_quick_select()[opt_range.cc:2214]
0000000140194375    mysqld.exe!test_if_skip_sort_order()[sql_select.cc:13222]
00000001401A1EFF    mysqld.exe!JOIN::exec()[sql_select.cc:1757]
00000001401A30CE    mysqld.exe!mysql_select()[sql_select.cc:2380]
00000001401A337F    mysqld.exe!mysql_explain_union()[sql_select.cc:16369]
000000014019901E    mysqld.exe!select_describe()[sql_select.cc:16310]
00000001401A1F5D    mysqld.exe!JOIN::exec()[sql_select.cc:2220]
00000001401A30CE    mysqld.exe!mysql_select()[sql_select.cc:2380]
00000001401A337F    mysqld.exe!mysql_explain_union()[sql_select.cc:16369]
00000001401617DA    mysqld.exe!execute_sqlcom_select()[sql_parse.cc:4961]
0000000140163306    mysqld.exe!mysql_execute_command()[sql_parse.cc:2204]
00000001401687B9    mysqld.exe!mysql_parse()[sql_parse.cc:5906]
000000014016935A    mysqld.exe!dispatch_command()[sql_parse.cc:1218]
000000014016A127    mysqld.exe!do_command()[sql_parse.cc:857]
00000001401FBA97    mysqld.exe!handle_one_connection()[sql_connect.cc:1115]
000000014026FCF5    mysqld.exe!pthread_start()
00000001403B5DF7    mysqld.exe!_callthreadstart()[thread.c:295]
00000001403B5EC5    mysqld.exe!_threadstart()[thread.c:275]
0000000077B6C3BD    kernel32.dll!BaseThreadInitThunk()
0000000077CB4581    ntdll.dll!RtlUserThreadStart()
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort...
thd->query at 00000000078EB410=explain select 1 from ( select count(distinct `c1`) from `t2`where  `c2` in (1,1) and `c3`
= 2 and `c4` = 3 group by `c2` ) x
thd->thread_id=1
thd->killed=NOT_KILLED