What to do if R has problem to access proxy server?

(Cited from Philipp Kauer, http://www.mail-archive.com/r-help@r-project.org/msg15104.html)


1) start R with option "C:\Program Files\R\R-2.6.2\bin\Rgui.exe" --
internet2
2) disable anything in your Rprofile.site and .Rprofile to have a
clean start of R