If you're having odd issues with RStudio (e.g. whitescreen of death, unresponsive taskbar, window will not launch etc.); you might try the following:
Delete the following files:
C: > users > username > AppData > Local > RStudio-Desktop
C: > users > username > AppData > Roaming > RStudio
Dive back into RStudio. (No restart required.)
Logic: The causes and symptoms can vary, but clearing these files flushes the program - data (working files) saved elsewhere will remain.