[R] Install packages not working in latest version?

[Neotropical bat risk assessments]

Seems that the latest version R version 2.9.0 (2009-04-17)
  has a glitch and will not install packages. Issue with unzipping?

Works fine with R version 2.8.1 (2008-12-22)


 > install.packages("ff")
--- Please select a CRAN mirror for use in this session ---
trying URL 'http://cran.fhcrc.org/bin/windows/contrib/2.9/ff_2.0.1.zip'
Content type 'application/zip' length 779664 bytes (761 Kb)
opened URL
downloaded 761 Kb

Error in .Internal(int.unzip(zipname, NULL, dest)) :
   no internal function "int.unzip"
 >
Bruce