Thomas Brand offers a tip for a weird, but annoying issue:
Have you ever tried to install OS X from a USB Flash Drive and received this error message?
This copy of the Install OS X Mavericks application can’t be verified. It may have been corrupted or tampered with during downloading.
The issue is not with your installation media, but rather with your Mac’s time and date. Follow these steps to set it right…
I’ve had this happen in the past, and it was maddening until I realized that it was the computer, not the media. This is a great tip to reset the date via the Terminal and go on your merry way.