This seems like a connectivity issue, R is not being able to connect to the CRAN repository you have selected, these are some things to try.
- Choose a different CRAN repository, RStudios repository is a good choice (http://cran.rstudio.com/) or you could choose one that is geographically closer to you.
- Disable secure download setting.
- Check if your internet connection has traffic restrictions of some kind, like a firewall, proxy server, etc. This is usually the case when you are at work or school.
