[R] unable to move temporary installation when install some packages

[PO SU]

Dear expeRts,
These days  i and some of my friends often encount   the same problem when installing packages, e.g. when i try to install.packages("stringi"), i will get :


package ‘stringi’ successfully unpacked and MD5 sums checked
Warning in install.packages :
  unable to move temporary installation ‘C:\Program Files\R\library\file28744050180\stringi’ to ‘C:\Program Files\R\library\stringi’

The downloaded binary packages are in
	C:\Users\po.su\AppData\Local\Temp\RtmpeobZut\downloaded_packages


But when i try to install some other packages, it is ok,like ggplot2,but my friends encount the same problem with ggplot2 like stringi for me.
we all use windows 7, and the latest version of Rstudio with R 3.1.1.
We investgate it, open the path dir 's modify permissions, it works for some packages,but for packages like Rcpp, the problem still come!
Is there some one happen to  know the solution?

--

PO SU
mail: desolator88 at 163.com 
Majored in Statistics from SJTU