Tcl/Tk not working on Mac OS X

Greetings.

Yesterday I decided to try out Rcmdr, but it refused to load.  I  
traced the problem to the library tcltk, which when I tried to load it  
told me this:

library(tcltk)

Loading Tcl/Tk interface ... Error in fun(...) :
  Can't find a usable init.tcl in the following directories:
    @TCL_IN_FRAMEWORK@ @TCL_IN_FRAMEWORK@



This probably means that Tcl wasn't installed properly.

Error : .onLoad failed in 'loadNamespace' for 'tcltk'
Error: package/namespace load failed for 'tcltk'

I then tried reinstalling R.  The R-GUI and R-Framework parts  
installed OK, but the gfortran and tcltk parts failed to install, even  
when trying to do so separately.

Other relevant information:
MacBook Pro, 15-inch, 2.16 Ghz, 3 GB RAM, 120 GB hard drive
Mac OS X 10.5.2

Any idea what's going on?  Thanks in advance for any help anyone can  
provide.

Aaron

-----
Aaron Solomon Adelman, PhD
Epidemiologist/statistician/computer expert
E-mail:  Aaron.Solomon.Adelman at gmail.com