Hi Alison,
Thank you for posting the query in Microsoft Community.
It would be great if you can answer the following questions:
1. Were there any changes made on the computer prior to the issue?
2. Do you get any error message? If yes, what is the complete and exact error message?
3. When exactly do you get the error message?
Please provide more information to assist you better.
Suggestions for asking a question on help forums