This was the first google result I found when searching for this same error message and problem. I dug around and found the last line of ~/Library/Caches/Micro

This was the first google result I found when searching for this same error message and problem. I dug around and found the last line of ~/Library/Caches/Microsoft/uls/com.microsoft.autoupdate2/logs/<hostname>-20150415-0724.log contained the following error: 04/15/2015 14:29:36.753 com.microsoft.autoupdate2 0x10e91f000 com.microsoft.autoupdate2 AutoUpdate.DownloadWindow ibcu7 Error File signature not verified: http://download.microsoft.com/download/7/0/C/70C26EA7-EF6D-4521-9805-BE8403739785/Office2011-1449Update_EN-US.dmg http://download.microsoft.com/download/7/0/C/70C26EA7-EF6D-4... 1C6F7480-A6A5-4D71-B86A-FFE6385302B0 I downloaded this .dmg myself and successfully installed it. After this, letting AutoUpdate pull and install the remaining three updates worked as expected.