Is Tableau Prep is installed on network drive or being accessed on a virtual machine? Does this behavior occur for any other programs? I personally use a Dell machine and do run into network issues, while Tableau Prep is running, but I have never had Tableau Prep close before.
I would also open a case with the Tableau Support team: Support Case | Tableau Software
Hope this helps!
You were right, the repository was located on a network drive which was seemingly causing the issue. After changing the repository to a local drive, this solved the problem. Fortunately we can now change the repository location as I don't think the earlier versions of prep allowed for this.