MySQL 4.1 se bloque avec "La base de données n'a pas été fermée normalement !"

De temps en temps, mon service MySQL 4.1 Windows se bloque avec les lignes suivantes dans le journal :

091218  9:31:25  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
091218  9:31:33  InnoDB: Starting log scan based on checkpoint at
InnoDB: log sequence number 2 817025450.
InnoDB: Doing recovery: scanned up to log sequence number 2 817025450
091218  9:31:35  InnoDB: Flushing modified pages from the buffer pool...
091218  9:31:35  InnoDB: Started; log sequence number 2 817025450
C:\Programme\MySQL\MySQL Server 4.1\bin\mysqld-nt: ready for connections.
Version: '4.1.14-nt'  socket: ''  port: 3306  Official MySQL binary

100107  9:02:51  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
100107  9:02:53  InnoDB: Starting log scan based on checkpoint at
InnoDB: log sequence number 2 953338420.
InnoDB: Doing recovery: scanned up to log sequence number 2 953338420
100107  9:02:53  InnoDB: Flushing modified pages from the buffer pool...
100107  9:02:53  InnoDB: Started; log sequence number 2 953338420
C:\Programme\MySQL\MySQL Server 4.1\bin\mysqld-nt: ready for connections.
Version: '4.1.14-nt'  socket: ''  port: 3306  Official MySQL binary

Ces messages ne pointent pas vers un problème spécifique. Que puis-je faire pour retrouver l'origine des pannes ?