Invalid connection error message when trying to write a file

I get an invalid connection method error message when trying to write an R
object from a user-defined function to my hard drive (running Windows 7)
using write.csv.  I have previously not had this problem with the same
user-defined function.  The error message is

Error in isOpen(file, "w") : invalid connection
In addition: Warning message:
In if (file == "") file <- stdout() else if (is.character(file)) { :
   the condition has length > 1 and only the first element will be used

Using
zz<-file(description="path","w")
write.csv(  )
close(zz)

creates an empty file but yields the same error message when I execute
write.csv.