SignTool unexepected internal error

I had the same issue but only when I'm trying to sign it under IIS/PHP script. When I run PHP from the console it's OK. And here there were no issue with account. Only one thing helped me - changing Anonymous Authentication Credentials for Site/application from Specific USER to Application pool identity.

I managed to fix it. Apperantly the user was corrupted.

after fixing the user using this KB from microsoft everything became right again.