title: Error in loadNamespace, object 'vI' not found with package plm
body: <p>I never had problems with installing packages before. 
  When I first tried to install the <code>plm</code> package, it gave me an error saying that package <code>pbkrtest</code> was not installed. So I tried installing <code>pbkrtest</code>, but <code>install.packages("pbkrtest")</code> did not work, it gave me this error message: </p>
  
  <blockquote>
    <p>install.packages("pbkrtest")
      Installing package into ‘C:/Users/Flo/Documents/R/win-library/3.2’
      (as ‘lib’ is unspecified)
      Warning in install.packages :
        package ‘pbkrtest’ is not available (for R version 3.2.2)</p>
  </blockquote>
  
  <p>I downloaded it manually from <a href="https://cran.r-project.org/src/contrib/Archive/pbkrtest/" rel="nofollow">https://cran.r-project.org/src/contrib/Archive/pbkrtest/</a> and put it into the respective directory. </p>
  
  <p>Moving on, I could now install plm. Nevertheless, I am now stuck with this error and cannot use the plm package: </p>
  
  <pre><code>library(plm)
  </code></pre>
  
  <blockquote>
    <p>Error in loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]]) : 
        object 'vI' not found<br>
      In addition: Warning message:<br>
    package ‘plm’ was built under R version 3.2.3<br>
      Error: package or namespace load failed for ‘plm’</p>
  </blockquote>
  
  <p>Here is my session info: </p>
  
  <pre><code>R version 3.2.2 (2015-08-14)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows 8 x64 (build 9200)
  
  locale:
  [1] LC_COLLATE=German_Germany.1252  LC_CTYPE=German_Germany.1252    LC_MONETARY=German_Germany.1252
  [4] LC_NUMERIC=C                    LC_TIME=German_Germany.1252    
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
  [1] dplyr_0.4.3    ggplot2_2.1.0  magrittr_1.5   stargazer_5.2  foreign_0.8-65 Formula_1.2-1 
  
  loaded via a namespace (and not attached):
   [1] Rcpp_0.12.3      knitr_1.12.3     MASS_7.3-43      munsell_0.4.3    colorspace_1.2-6
   [6] lattice_0.20-33  R6_2.1.2         plyr_1.8.3       tools_3.2.2      parallel_3.2.2  
  [11] nnet_7.3-10      grid_3.2.2       nlme_3.1-125     gtable_0.2.0     DBI_0.3.1       
  [16] lmtest_0.9-34    assertthat_0.1   bdsmatrix_1.3-2  sandwich_2.3-4   scales_0.4.0    
  [21] zoo_1.7-12 
  </code></pre>