A little while ago, I encountered a very frustrating issue that had me pulling my hair out for a while. That is, until I finally stumbled upon the fix for the issue.
As a registered developer, I've been testing out Mavericks since Developer Preview 3, and I made it a habit of installing every release up until the GM version. The nice thing about the Mavericks betas is that you can grab the updates directly from the Mac App Store without having to completely reinstall the OS once a new beta ships.
That all changed when Apple released a stealth (13A603) GM update a few days ago, which didn't feature an update in the Mac App Store. Either you needed to completely reinstall with the new GM build, or just deal with the outdated (13A598) GM build until hopefully OS X 10.9.1 places you back on the correct upgrade path.
Sure this was annoying, but it didn't sound like a huge deal to me until I wanted to download Mavericks this evening in order to make a USB install key, and was continuously met with an error message.