[MacRuby-devel] posix_spawn Permission denied

Hi, I am building some applications for the first time and when I transfer them over to a new computer I am getting a posix_spawn permission denied error. I read a bit about this on the net and it seems it can be caused by dropbox. I use dropbox to transfer my files but they are always zipped. Does anyone have any suggestions as to other causes with the posix_spawn permission denied error? Thanks, Shaun