Remember, this is just a story, from the injured party's point of view. And its all hearsay to us.
Eventually I gave up and ate the slightly worse prices at Expedia. No bugs, easier to pick a flight, and no obnoxious William Shatner-oriented graphic design.
I am not sure if this is a bug in Priceline. I've seen the same with Orbitz last week. Moreover, with Orbitz fares reduced or became unavailable while trying to book.