[R-SIG-Mac] Problem with R 3.0.1

[Chen, Gang (NIH/NIMH) [C]]

R 3.0.1 does not seem to work properly on two of my Mac notebooks, one with 10.8.2 and the other 10.6.8. When I start R on the terminal, I get the following:

Error in .Call("R_isMethodsDispatchOn", onOff, PACKAGE = "base") :
  "R_isMethodsDispatchOn" not available for .Call() for package "base"

R version 3.0.1 (2013-05-16) -- "Good Sport"
...

Even the following does not work:

> citation()
Error: could not find function "citation"

However, once I downgraded R from 3.0.1 to 3.0, everything works fine. What could be the source of the problem?

Thanks!

Gang