Hi,
I experienced almost exactly the same issue today (October 26, 2026) on Windows 11.
I was using Python 3.11.15, Pandas 3.1.0, and Visual Studio Code with Smart App Control enabled.
When importing Pandas, I received the same error (Event ID 3077). Windows blocked the file strptime.cp311-win_amd64.pyd.
I checked the file's digital signature using PowerShell (Get-AuthenticodeSignature), and the result was NotSigned.
Since I currently need Pandas for my project, I decided to try an older version instead.
I created a new virtual environment and installed Pandas 2.2.3:
uv venv .venv-test --python 3.11
uv pip install --python .venv-test pandas==2.2.3
This worked for me! I can now import Pandas without any issues, and Smart App Control is still enabled.
I'm not sure why version 3.1.0 is being blocked, but it might be related to how Windows evaluates the newer binary files.
I hope this helps you as a temporary workaround!