(Post moved and 'setenv' added to topic.)
There are a lot of 'setenv' commands in install.com, so the error message has no context in the absence of any other information.
One possibility is that the pathname for the CHARMM source, or the MPI library, etc., may have a space character in the name.
One thing you can try is to change the first line of install.com from
#!/bin/csh -f -x
Adding the -x flag will echo the commands as they are executed; you may wish to redirect the output to a file, or use 'less' to see it a page at a time.