[R] Problem loading packages in R 2.13.0 on Mac

[Adrienne Keller]

I am having problem loading packages in the newest version of R  
(2.13.0) on my Mac. I have tried to install various packages (e.g.  
lawstat, Rcmdr, car) and load them using the Package Installer and  
Package Manager menu options but I get the follow error:

 > library(lawstat)
Loading required package: mvtnorm
Error: package 'mvtnorm' could not be loaded
In addition: Warning message:
In library(pkg, character.only = TRUE, logical.return = TRUE, lib.loc  
= lib.loc) :
   there is no package called 'mvtnorm'

When I click on the box for loading lawstat in the Package Manager, it  
immediately reverts back to an unchecked box.

I have tried to load mvtnorm and then load lawstat but I get the same  
error.

Help?

Thanks,

Adrienne