Very small MySQL table keeps crashing
The first—and most important—thing you can do before repairing a corrupted table is to back it up. Never try running a repair operation on a table without backing it up; if you fail, your data might be in worse shape than originally and may even become un-salvageable. Backing up the original table file allows you the option of trying a different technique if your first attempt doesn't work.

Next, shut down the MySQL server. This is because myisamchk makes changes to the table file itself, so you don't want other users accessing or otherwise manipulating the file during the repair operation. Remember, don't just terminate the server with a call to "kill"; instead, use the mysqladmin SHUTDOWN command to ensure that MySQL closes all open tables gracefully and doesn't further compound your problem.

myisamcheck will be enough to get details regarding what is causing table to crash for more details you can refer this http://dev.mysql.com/doc/refman/5.0/en/myisam-check.html