A very quick one today , Myob Setup Failed error - 0x800b0101
A required certificate is not within its validity period when verifying against the current system clock or the timestamp int he signed file.
This error occurs because the digital timestamp has expired and is no longer valid as stated by the error, you have two solutions.
Solution 1: Roll back your Clock and Retry the installation
right click your file and go to properties, under the Digital Signatures tab you will see when the file was timestamped , in my case Saturday 7 Feb 2015. As far as I know a timestamp lasts about 2-3 months sometimes longer
Wind your clock back to this timestamp date and reinstall.
Solution 2: Visit the MYOB site and re-download
Visit the myob site and re-download the site, it will have a fresh timestamp from the day you downloaded it. Useful options for those not administratively privileged to change the time.
That's all folks, not sure the reasoning for timestamps but there must be a reason