Aconteceu comigo também. Não é um vírus (é o que eu também pensei). Aqui está a explicação:
On occasion, when rebooting Windows, you might see a black scren, with a Windows logo in center, and white text below rapidly counting the application of thousands of "update operations," like this:
Component-based servicing is a multi-step process, some steps of which
you normally don't see:
- Download digitally-signed updates
- Verify signatures
- Unpack into a staging area
- Perform staging operation
- Begin reboot
- Validate correctness of staged updates
- Migrate staged updates into WinSxs and the registry
- Validate correctness of merge
- Finalize reboot
- Display logon screen
Step 4 is the pre-reboot "Do not interrupt or power down" message
while you see a count from 0% to 100%. Step 7 is the post-reboot
version. Ordinarily, there is no visible indication of steps 6 and 8.
But if something causes the validation to fail, updates are re-staged.
In this case, the validation steps become visible, and that's the
image you see above. This does not mean Windows is applying thousands
of updates. Instead, the batch of updates being installed contain
thousands of distinct update operations, and you're experiencing the
rare opportunity to witness a status message as each operation
proceeds.
In the case of a major OS components like, say, the .NET framework,
applying the update package requires processing possibly thousands of
steps: each existing registry entry has to be read, modified, and
validated. Each DLL has to be extracted, verfied, copied, and
validated. Installing one update involves applying many many update
operations.
Fonte: link