Hi Robert_Porter,
I'm Nik, an independent advisor here to assist you with this.
Please try to clear cached MS Teams login password from credentials manager ad see if this helps:
- Open the Credentials Manager (Control Panel > User Accounts > Credential Manager)
- Select Windows Credentials
- Under Generic Credentials, you will see one called: msteams_adalsso/adal_context_segments.
- Delete them
- Sign out and Sign-in again
- Try accessing Ms teams app again
Regards
Nik