[Freesurfer] memory allocation error with mris_register for one subject

hello!

i am able to run mris_register on all of the OASIS brain images that i have tested except for one: OAS1_0061_MR1:

mris_register -curv OASIS-0061_MR1/surf/rh.sphere templates/freesurfer/rh.OASIS_template.tif OASIS-0061_MR1/surf/rh.sphere_to_OASIS_template.reg using smoothwm curvature for final alignment $Id: mris_register.c,v 1.59 2011/03/02 00:04:33 nicks Exp $ $Id: mrisurf.c,v 1.693.2.2 2011/04/27 19:21:05 nicks Exp $ reading surface from OASIS-0061_MR1/surf/rh.sphere... TAGskip: tag=1717658469, failed to calloc 1868656640 bytes! Cannot allocate memory

the .sphere files are the same size, but i get a memory error. any idea why this might be?

cheers, @rno