Hi @rob7!
I think @squeezer44 might have been trying to find out if maybe the hang happens when RStudio tries to start up R, in which case the culprit might be a problem with your R installation. (If you read that sentence and suddenly felt 
, you might want to take a look at: Differentiating R from RStudio).
Do you remember how you installed R?
Can you open Rgui.exe (the simple GUI that gets installed when you install R)? Does it seem to work OK? What do you get if you run sessionInfo() from the console in Rgui.exe?