double dyn.load hang up

I had a rather mysterious problem that now seems to have been
attributable to dyn.load()ing the same object twice in one R session
and I would be curious to know if this is a known issue, or something
that I should try to document further:

I had a single fortran subroutine which I was making into a .so file
with the usual R CMD SHLIB ritual.  Then I would run a test problem
which involved dyn.load()ing the .so object, sourcing an R function
that called .Fortran, generating some random data and finally invoking
the R function when I sourced a file that looked like this:

# Initial test of parq algorithm
p <- 30
n <- 200
x <- matrix(rnorm(p*n),n,p)
y <- rnorm(n)
dyn.load("parq.so")
source("parq.q")
z <- parq(x,y,lambda = -1)

That is z contained a perfectly sensible result, but when I sourced  
this
file a second time and then tried to look at "z"  the R process  
hung.  This
happened on both my old G5 desktop running 2.7.1 and on a new intel
mac-pancake running 2.7.1.  However, on several other machines 3
linuxes and one solaris everything was copasetic, no hangups after
the second invocation.

After much agonizing under the assumption that there was something
wrong with memory allocation in my fortran -- a hypothesis that had
quite a lot of historical support -- I finally tried just running  
the parq
function without the double  invocation of dyn.load  and this worked
perfectly.  From which I draw the moral:

	Don't dyn.load twice, it's not (mac)-nice.

url:    www.econ.uiuc.edu/~roger            Roger Koenker
email    rkoenker at uiuc.edu            Department of Economics
vox:     217-333-4558                University of Illinois
fax:       217-244-6678                Champaign, IL 61820