I have upgraded R to version 3.2.2.
When I restart Rstudio, before ">" is shown, there is an error message:
Error in tools:::httpdPort <= 0L :
comparison (4) is possible only for atomic and list types
Upgrade your RStudio version to the latest one, should work in any OS.
For Linux/Ubuntu 14.04 terminal users, simply do:
sudo apt-get remove rstudio wget https://download1.rstudio.org/rstudio-0.99.489-amd64.deb sudo dpkg -i rstudio-0.99.489-amd64.deb
Now, run RStudio. The error message should disappear.