R13B02-1: badmatch in memsup:get_memory_usage

[Winston Smith]

Running R13B02-1 on Mac OS 10.6.2 (x86_64), I'm seeing the following
error when I start my OTP application:

=SUPERVISOR REPORT==== 17-Oct-2009::00:10:08 ===
     Supervisor: {local,os_mon_sup}
     Context:    child_terminated
     Reason:     {{badmatch,{error,{fread,input}}},
                  [{memsup,get_memory_usage,1},
                   {memsup,'-handle_info/2-fun-0-',2}]}
     Offender:   [{pid,<0.74.0>},
                  {name,memsup},
                  {mfa,{memsup,start_link,[]}},
                  {restart_type,permanent},
                  {shutdown,2000},
                  {child_type,worker}]


Not sure how to diagnose this further ...