"02/15/2016 5PM
I call it Valentine's Day 2016 bug
I have found an installer bug with OS X. (actually expired Apple security cert.) I've tested it with 10.9.5, 10.10.5 and 10.11.3. If you try to install OS X onto a drive you will get the common install error

"This copy of the Install OS X - applications cannot be verified. It may have been corrupted or tampered with during downloading."

Normally this is fixed by changing the date to the proper date. HOWEVER, the only way to fix it is actually by setting it to an older date. I set my clock to Feb 13th and the installer worked. I thought I had a bad data cable or bad drive, logicboard. etc. But after trying to install operating systems on 3 different machines I knew it had to be something else.

Only setting the clock back (to Feb. 13th or I assume more) solved the issue. I wanted to report this to your readers as this can be a critical issue.
- Lawrence R."

I assume Apple will update installers for the new certificate. (Maybe by the time you read this.)

While on the subject of expired/renewed Apple security certificates, in case any Snow Leopard users missed it late last month, Apple posted a Mac App Store Update for OS X 10.6.8 with updated certificate.
  

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• Yamaha AV Controller iOS App v4.40:
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• If you changed the date to May 1970 or earlier and can't restart your iPhone, iPad, or iPod touch (contact apple support until update to fix is released)
  
  
• Dictation commands you can use in OS X
• OS X Yosemite: Use Dictation Commands to tell your Mac what to do

Topic-based page of How-To, Troubleshooting & Tips for Mac/OS X/iOS Users.