I click the signature box and a dark overlay appears all over the document, with 1 white pixel in the middle.
I can press esc to go back.
thats it... help please
We apologize for the inconvenience caused, as per the description above, you are not able to sign a PDF file as getting a dark box, Is that correct?
Please check for any pending updates from Help>Check for updates, reboot the machine after the installation of updates.
You can also repair the installation files in Acrobat from Help>Repiar installation(only for Windows). Reboot the machine and see if this makes any difference.
Make sure that you are logged in with your current Adobe ID and password in Acrobat.
If the issue persists, please share the following details:
Let us know how it goes and share your findings.