MySQL keeps crashing: InnoDB: Unable to lock ./ibdata1, error: 11

I have a simple webserver (Debian 6.0 x86, DirectAdmin with 1 GB of memory and still 10 GB free space, mySQl version 5.5.9), however the mySQL server keeps crashing and I need to kill all mySQL processes to be able to restart it again.

/var/log/mysql-error.log output:

130210 21:04:26 InnoDB: Using Linux native AIO
130210 21:04:34 InnoDB: Initializing buffer pool, size = 128.0M
130210 21:05:42 InnoDB: Completed initialization of buffer pool
130210 21:05:48 InnoDB: Initializing buffer pool, size = 128.0M
130210 21:06:22 InnoDB: Initializing buffer pool, size = 128.0M
130210 21:06:27 mysqld_safe mysqld from pid file /usr/local/mysql/data/website.pid ended
130210 21:06:29 mysqld_safe mysqld from pid file /usr/local/mysql/data/website.pid ended
130210 21:07:22 InnoDB: Completed initialization of buffer pool
130210 21:07:51 mysqld_safe mysqld from pid file /usr/local/mysql/data/website.pid ended
130210 21:08:33 InnoDB: Completed initialization of buffer pool
130210 21:12:03 [Note] Plugin 'FEDERATED' is disabled.
130210 21:12:47 InnoDB: The InnoDB memory heap is disabled
130210 21:12:47 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
130210 21:12:47 InnoDB: Compressed tables use zlib 1.2.3
130210 21:12:47 InnoDB: Using Linux native AIO
130210 21:13:11 InnoDB: highest supported file format is Barracuda.
130210 21:13:23 InnoDB: Initializing buffer pool, size = 128.0M
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
130210 21:14:05  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
130210 21:17:53  InnoDB: Unable to open the first data file
InnoDB: Error in opening ./ibdata1
130210 21:17:53  InnoDB: Operating system error number 11 in a file operation.

I have found a topic on the mySQL website here however there's no solution for it.

Any ideas anyone?