Several users report that their Monday began with the message, "Your version of QuickTime 5 has expired." We have covered this issue previously, and are noting it today for those users who were caught by surprise. See this MacFixIt Forums QuickTopic (QuickTime 5.0.1), VISEData errors coverage, and especially the Preview expiration warning item for more.
Update: David Gillaspy adds: "When my QuickTime 5 beta expired this morning, I got an error message on boot up about Vbox refusing to load. This meant that in addition to QuickTime 5 not working, my copy of GoLive wouldn't work either." We are not sure why this is happening, nor if it is an indication that Apple is using Vbox for QuickTime, however, it tends to confirm our previously noted concern that Vbox can cause some unexpected problems.