[R] have difficulty in installing packages

[Seungho Huh]

Dear sir or ma'am,

I have difficulty in installing packages. When I click "Install package(s)..." in the Packages menu, it takes forever and it finally shows the following message: 

--- Please select a CRAN mirror for use in this session ---
Warning: unable to access index for repository http://www.ibiblio.org/pub/languages/R/CRAN/bin/windows/contrib/2.2
Warning: unable to access index for repository http://www.stats.ox.ac.uk/pub/RWin/bin/windows/contrib/2.2
Error in install.packages(NULL, .libPaths()[1], dependencies = TRUE, type = type) : 
        no packages were specified

In fact, I visited http://www.r- project.org/, looked for some CRAN mirror sites, and decided to click the following site: http://www.ibiblio.org/pub/languages/R/CRAN/ However, the ckicking function simply did not work for this site and all the other CRAN mirror sites listed there. 
Is this a problem that I will need to get help from the help desk of my company? Or, has someone else had similar problems? Thanks for any advice on this.