Help, MYSQL crashed!

[The extros]

10/6/2012 20:38:30] mysql_real_query(): DELETE FROM `account_viplist` WHERE `account_id` = 9963078 AND `world_id` = 0 - MYSQL ERROR: Incorrect key file for table '.\ancore\account_viplist.MYI'; try to repair it (126)

Why it happens?? where i have to put : REPAIR TABLE `tablename`;
and it happens suddenly??, how can I prevent if from happening... please help me!

MySQL said:

#145 - Table '.\ancore\account_viplist' is marked as crashed and should be repaired

 

[The extros]

bring
up
my
post

 

[Ninja]

REPAIR [COLOR=#993333][B]TABLE[/B][/COLOR] [COLOR=#ff0000]`account_viplist`[/COLOR];

 

[The extros]

where do i have to put it?? on mysql queries.., on account_viplist?
please help me... and how can i prevent this kind of events... How do they happen??