I'm getting a Runtime Error after after loading then Sonar X3 crashes and requires a reboot. The Runtime error shows the path of the program followed by the following: "R6025 Pure Virtual Function Call".

Hi, and welcome to this forum. Which version of Windows do you have? Is your Windows fully up to date? IIRC some of the C++ updates can make a difference.
All the best.

I have windows 10 home 64 bit running on a Lenovo desktop with Inteli5-3470S QC 2.9GHZ Intel HD Graphics. I reinstalled my X3 on this machine in Sept 2016. It ran super, I recorded a lot, no issues, ran super fast. Then on 12/6/2016 I got the  "R6025 Pure Virtual Function Call" error. X3 became unstable, unusable and always crashed. I noticed that Microsoft loaded new updates on my pc the same day, 12/6! The update was for Silverlight and it included visual basic c++2012 and c++2013 Redistributable. I had to delete those updates and re-install X3, now it seems ok. But, what happened? is X3 not compatible with these? I'm concerned this will just keep happening because you can't turn off or monitor updates in Win10 home. I also noticed other random reports of Cakewalk customers having the same error message with other products. 

Do a google search of "windows 10 home turn off auto updates". You can do it. This is exactly why I never let it happen automatically.

I am getting the same error with Sonar Platinum after upgrading.