I got the following error when I started RStudio (In Windows 7, R version 3.4.0, RStudio version 1.0.143):
The program cant start because libxml2-2.dll is missing from your computer.
Try reinstalling the program to fix the problem.
It took an effort to find out what was causing the problem, until eventually I run onto similar post here: GGobi in rattle in R is not initializing and it helped.
The solution was as easy as just running a single command (right from RStudio): install.packages("rggobi") (Or from Tools->Install Packages menu). - And it fixed it !