Hi Ben,
Something is triggering the account logout (most likely something is trying to login with an old credential). In the past, I have seen a person's machine/phone trying to use AD credentials to connect to WiFi (if you use Radius/NPS) to authenticate.
If it isn't WiFi, then it is some application trying again and again with wrong/expired credentials.
If this is helpful please accept as answer or upvote.
Best regards,
Dillon Silzer, Director | Cloudaen.com | Cloudaen Computing Solutions