Membase server randomly exiting/crashing

Hello there, We're currently running some tests to work out if membase is a viable solution for us. However we seem to be encountering random crashes/graceful exits. We can't determine exactly why this is but here is an output from browse_logs. Perhaps someone can point us in the right direction as to why this may be happening? Log is as follows:

PROGRESS REPORT <5650.7.0> 2011-01-20 14:56:05
===============================================================================
application mnesia
started_at 'ns_1@127.0.0.1'

CRASH REPORT <5650.116.0> 2011-01-20 14:56:05
===============================================================================
Crashing process
initial_call {ns_mnesia,init,['Argument__1']}
pid <5650.116.0>
registered_name []
error_info
{exit,{{case_clause,{aborted,{badarg,schema,unknown}}},
[{ns_mnesia,ensure_schema,0},
{ns_mnesia,init,1},
{gen_server,init_it,6},
{proc_lib,init_p_do_apply,3}]},
[{gen_server,init_it,6},{proc_lib,init_p_do_apply,3}]}
ancestors [ns_server_sup,ns_server_cluster_sup,<5650.52.0>]
messages []
links [<5650.125.0>,<5650.72.0>]
dictionary []
trap_exit true
status running
heap_size 377
stack_size 24
reductions 257

SUPERVISOR REPORT <5650.72.0> 2011-01-20 14:56:05
===============================================================================
Reporting supervisor {local,ns_server_sup}

Child process
errorContext start_error
reason
{{case_clause,{aborted,{badarg,schema,unknown}}},
[{ns_mnesia,ensure_schema,0},
{ns_mnesia,init,1},
{gen_server,init_it,6},
{proc_lib,init_p_do_apply,3}]}
pid undefined
name ns_mnesia
start_function {ns_mnesia,start_link,[]}
restart_type permanent
shutdown 10000
child_type worker

ERROR REPORT <5650.99.0> 2011-01-20 14:56:05
===============================================================================
rb: ERROR! A report on bad form was encountered. It can not be printed to the log.

Details:
"2011-01-20 14:56:05" {{{2011,1,20},{14,56,5}},
{error_report,<5650.51.0>,
{<5650.99.0>,std_error,
{mochiweb_socket_server,235,
{child_error,shutdown}}}}}

rb: Logging resumed...

SUPERVISOR REPORT <5650.54.0> 2011-01-20 14:56:05
===============================================================================
Reporting supervisor {local,ns_server_cluster_sup}

Child process
errorContext start_error
reason shutdown
pid undefined
name ns_server_sup
start_function {ns_server_sup,start_link,[]}
restart_type permanent
shutdown infinity
child_type supervisor

INFO REPORT <5650.7.0> 2011-01-20 14:56:05
===============================================================================
application ns_server
exited {shutdown,{ns_server,start,[normal,[]]}}
type temporary