Hello, The following error message: <snip> >---------------------------------------------------------------------------- >Unknown message tag (-32766) received by 1 >UUnknUkUnknknonwonwonwown nm nm nm mesessessesssagaegaegaege t at at >atag g( g( g( (-3-23-23-232767667667666) )r )r )r >reececeeceeceiivevievievedd b db db byy 2 y3 y4 5 >----------------------------------------------------------------------------- </snip> is actually four error message that have been "intercolated" by MPI. All worker output to stderr or stdio is displayed by the master node one byte at a time and on a first come, first serve basis. In this case, it appears that an unknown message tag was broadcast to each of the worker nodes (causing each to print the an error message and exit). You mentioned that the master node may be using a different version of mpiBLAST -- this may be the cause of the errors. Since message tags are used by the master to request database sequences cached in the memory of the worker nodes, it is crucial that both master and worker nodes use the same dictionary of message tags. If you continue to get errors, please let me know. Regards, Jason Gans Bioscience Division, B5 Los Alamos National Laboratory