hello all For those interested! i figured out the problem! I needed to put the dyn.load and dyn.unload lines inside the loop! ---------------------------------------------------------------------------------------------------- library(doMPI) cl <- startMPIcluster(count=2) #this will be changed later registerDoMPI(cl) #the input parameters! ... #some vecs and matrices for the C program ... #load the C code Est_Results<-foreach(data_iter = 1:nsamp, .combine="cbind", .inorder=TRUE ) %dopar% { dyn.load("/export/home/example/Runs/eg.so") outs=.C("prog1", all of the args ) do more things dyn.unload("/export/home/example/Runs/eg.so") return( some things) } closeCluster(cl) save.image("/export/home/example/Runs/eg.RData") mpi.quit(save = "no") ---------------------------------------------------------------------------------------------------- ### UNIVERSITY OF CAPE TOWN This e-mail is subject to the UCT ICT policies and e-mai...{{dropped:16}}