Hi @Clare East
To isolate issues with desktop apps, try signing into the Teams web client in private mode to check if the issue persists.
Based on your description, it appears that there is unusual activity, such as someone entering a password too many times. Follow this article to unlock your account: Account has been locked.
Alternatively, you can contact your administrator to populate the admin center diagnostics below.
- Run Tests: Teams Sign-in
- In the Username or Email Address field, enter the email address of the user who's experiencing the Teams sign-in issue.
For more details about sign-in error, you could refer to: Resolve sign-in errors in Teams.
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