Corrupt database table

I received this error while checking my database:

[nobl34_wp99.wp_redirection_404] Table is marked as crashed    
 [nobl34_wp99.wp_redirection_404] 3 clients are using or haven't closed the table properly    
 [nobl34_wp99.wp_redirection_404] Found key at page 56320 that points to record outside datafile    
 [nobl34_wp99.wp_redirection_404] Corrupt

I repaired the database to fix this issue. What would have caused the table to corrupt and what should I do to prevent this issue in the future?