R programming language breaks and must be reinstalled

Yesterday, I tried to open the R programming environment by typing "R" at the command line. I was met with the following error message: Fatal error: unable to open the base package I didn't know what to do about that, so I re-installed R. That fixed the problem, so I went on with my day. Today, I am met with the same error when I type "R" at the command line. I am bamboozled!