error: Lock wait timeout exceeded; try restarting transaction

[justin ux]

hi,
I am using a mysql 5.0.20 cluset with 2 datanodes ,2 mysqld nodes and a mgm node on 3 sun solaris 10 servers.
I got lots of error lilke :
060710 10:16:46 [ERROR] /usr/local/mysql/bin/mysqld: Sort aborted
060710 10:17:36 [ERROR] /usr/local/mysql/bin/mysqld: Lock wait timeout exceeded; try restarting transaction
060710 10:17:36 [ERROR] /usr/local/mysql/bin/mysqld: Sort aborted
060710 10:18:26 [ERROR] /usr/local/mysql/bin/mysqld: Lock wait timeout exceeded; try restarting transaction
060710 10:18:26 [ERROR] /usr/local/mysql/bin/mysqld: Sort aborted
060710 10:19:16 [ERROR] /usr/local/mysql/bin/mysqld: Lock wait timeout exceeded; try restarting transaction
060710 10:19:16 [ERROR] /usr/local/mysql/bin/mysqld: Sort aborted
060710 10:20:06 [ERROR] /usr/local/mysql/bin/mysqld: Lock wait timeout exceeded; try restarting transaction
060710 10:20:06 [ERROR] /usr/local/mysql/bin/mysqld: Sort aborted

It occurs every tens seconds for many days, but there was no query or process excuted in mysql server.

mysql> show processlist;
+-------+------+--------------------+------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+-------+------+--------------------+------+---------+------+-------+------------------+
| 22829 | root | Cronus:45074 | gmms | Sleep | 47 | | | |
| 23645 | root | Cronus:64598 | gmms | Sleep | 1566 | | |
| 23646 | root | localhost | gmms | Query | 0 | | show processlist |
| 23648 | root | Cronus:64954 | gmms | Sleep | 1170 | | |
| 23649 | root | Cronus:64985 | gmms | Sleep | 989 | | |
+-------+------+--------------------+------+---------+------+-------+------------------+

I can not find any reason. Can somebody help me?

Thanks in advance!
Justin