I managed to solve this, thanks to the link supplied above (ie https://support.rstudio.com/hc/en-us/articles/360017886674-Troubleshooting-RStudio-Rendering-Errors).
When I tried to change the "Rendering Engine" within RStudio by selecting the dropdown box on the Tools > Global Options > General > Advanced tab, my RStudio again crashed like before.
So instead, I went into my desktop.ini file in the %APPDATA%\Roaming\RStudio\ folder and added desktop.renderingEngine=software under the General section and this seemed to fix the problems I was having.
Thanks to kevinushey for the solution!