I get this notification when I try to close the file I am translating. Also the same pop-up appears when I try to close Studio. I am 70% into the translation of a 100 pages file, 

I get this notification when I try to close the file I am translating. Also the same pop-up appears when I try to close Studio. I am 70% into the translation of a 100 pages file, 

 Galatia Shiacola 

You got that far why not post the entire message!  That would tell us what version you're using, what operating system you have and also exactly where the object reference error occurred.  There is nothing in the information you are providing that helps us to help you at all.

You can copy the entire code (stack trace) and paste it into here:

In the mean time, what happens when you press Ctrl+S?  Can you save the file and your progress?  Have you saved your translations into a translation memory?  If you have then just kill the application with the task manager and restart.