This is one of the many random Tables that get corrupted. Any ideas why and what would be causing this?
 
**How do I keep MySQL tables from crashing and MySQL from crashing?** 

    Repairing USR_wp537
    
    USR_wp537.rev_commentmeta                     OK
    USR_wp537.rev_comments                        OK
    USR_wp537.rev_links                           OK
    USR_wp537.rev_options                         OK
    USR_wp537.rev_postmeta                        OK
    USR_wp537.rev_posts
    Error    : Incorrect key file for table './USR_wp537/rev_posts'; try to repair it
    Error    : Incorrect key file for table 'rev_posts'; try to repair it
    error    : Corrupt
    USR_wp537.rev_term_relationships              OK
    USR_wp537.rev_term_taxonomy                   OK
    USR_wp537.rev_terms                           OK
    USR_wp537.rev_usermeta                        OK
    USR_wp537.rev_users      

 Eventually the only way to fix is to do a `mysql> REPAIR TABLE <tbl> USE_FRM;`

This is also mysql 5.5

> top - 20:17:11 up 4 days,  8:57,  1 user,  load average: 0.41, 0.37,
> 0.36 Tasks: 204 total,   1 running, 203 sleeping,   0 stopped,   0 zombie Cpu0  : 11.0%us,  0.3%sy,  0.0%ni, 88.7%id,  0.0%wa,  0.0%hi, 
> 0.0%si,  0.0%st Cpu1  :  5.0%us,  1.0%sy,  0.0%ni, 93.4%id,  0.0%wa,  0.0%hi,  0.7%si,  0.0%st Cpu2  : 10.4%us,  0.7%sy,  0.0%ni, 89.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st Cpu3  :  1.3%us,  0.3%sy,  0.0%ni, 98.0%id,  0.0%wa,  0.0%hi,  0.3%si,  0.0%st Mem:  16288440k total, 15292940k used,   995500k free,  1398928k buffers Swap:  8191992k
> total,        0k used,  8191992k free,  9351404k cached

my.cnf

    [mysqld]
    core-file
    default-storage-engine=MyISAM
    local-infile=0
    symbolic-links=0
    skip-networking
    max_connections = 500
    max_user_connections = 40
    key_buffer = 500M
    myisam_sort_buffer_size = 32M
    join_buffer_size = 256M
    read_buffer_size = 2M
    sort_buffer_size = 2M
    read_rnd_buffer_size = 2M
    table_cache = 1024
    thread_cache_size = 16K
    wait_timeout = 20
    connect_timeout = 10
    tmp_table_size = 256M
    max_heap_table_size = 256M
    max_allowed_packet = 160M
    max_connect_errors = 10
    query_cache_limit = 1M
    query_cache_size = 64M
    query_cache_type = 1
    low_priority_updates=1
    concurrent_insert=ALWAYS
    log-error=/var/log/mysql/error.log
    myisam_repair_threads=4
    [mysqld_safe]
    core-file-size = unlimited
    open_files_limit = 8192
    log-error=/var/log/mysql/error.log
    
    [mysqldump]
    quick
    max_allowed_packet = 512M
    
    [myisamchk]
    key_buffer = 64M
    sort_buffer = 64M
    read_buffer = 16M
    write_buffer = 16M

EDIT:
Looks like MySQL for some reason did a restart?

    130131 20:30:59 [ERROR] Got an error from thread_id=817995, /builddir/build/BUILD/mysql-5.5.28/mysql-5.5.28/storage/myisam/mi_write.c:223
    130131 20:30:59 [ERROR] MySQL thread id 817998, OS thread handle 0x7f8589e2a700, query id 24842525 localhost ahmad_wp Waiting for table level lock
    SELECT option_value FROM wp_options WHERE option_name = 'widget_momizat-posts-images' LIMIT 1
    130131 20:30:59 [ERROR] MySQL thread id 817995, OS thread handle 0x7f858692f700, query id 24842524 localhost ahmad_wp update
    INSERT INTO `wp_options` (`option_name`, `option_value`, `autoload`) VALUES ('rewrite_rules', 'a:91:{s:27:\"typename/([0-9]{4})/(.+)/?$\";s:30:\"index.php?typename=$matches[2]\";s:47:\"category/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$\";s:52:\"index.php?category_name=$matches[1]&feed=$matches[2]\";s:42:\"category/(.+?)/(feed|rdf|rss|rss2|atom)/?$\";s:52:\"index.php?category_name=$matches[1]&feed=$matches[2]\";s:35:\"category/(.+?)/page/?([0-9]{1,})/?$\";s:53:\"index.php?category_name=$matches[1]&paged=$matches[2]\";s:17:\"category/(.+?)/?$\";s:35:\"index.php?category_name=$matches[1]\";s:44:\"tag/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$\";s:42:\"index.php?tag=$matches[1]&feed=$matches[2]\";s:39:\"tag/([^/]+)/(feed|rdf|rss|rss2|atom)/?$\";s:42:\"index.php?tag=$matches[1]&feed=$matches[2]\";s:32:\"tag/([^/]+)/page/?([0-9]{1,})/?$\";s:43:\"index.php?tag=$matches[1]&paged=$matches[2]\";s:14:\"tag/([^/]+)/?$\";s:25:
        130131 20:33:42 mysqld_safe Number of processes running now: 0
        130131 20:33:42 mysqld_safe mysqld restarted
        130131 20:33:42 [Note] libgovernor.so found
        130131 20:33:42 [Note] All governors functions found too
        130131 20:33:42 [ERROR] Governor not connected
        130131 20:33:42 [Note] All governors lve functions found too
        130131 20:33:42 [Note] Plugin 'FEDERATED' is disabled.
        130131 20:33:42 InnoDB: The InnoDB memory heap is disabled
        130131 20:33:42 InnoDB: Mutexes and rw_locks use GCC atomic builtins
        130131 20:33:42 InnoDB: Compressed tables use zlib 1.2.3
        130131 20:33:42 InnoDB: Using Linux native AIO
        130131 20:33:42 InnoDB: Initializing buffer pool, size = 128.0M
        130131 20:33:42 InnoDB: Completed initialization of buffer pool
        130131 20:33:42 InnoDB: highest supported file format is Barracuda.
        InnoDB: The log sequence number in ibdata files does not match
        InnoDB: the log sequence number in the ib_logfiles!
        130131 20:33:42  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...
        130131 20:33:42  InnoDB: Waiting for the background threads to start
        130131 20:33:43 InnoDB: 1.1.8 started; log sequence number 5726524860
        130131 20:33:43 [Note] Event Scheduler: Loaded 1 event
        130131 20:33:43 [Note] /usr/sbin/mysqld: ready for connections.
        Version: '5.5.28-cll-lve'  socket: '/var/lib/mysql/mysql.sock'  port: 0  MySQL Community Server (GPL)