This isn't a bug, but it's something that's come up a few times now, so I thought I would mention it.
As part of the primary project I'm using PL on at the moment there are people at the client's company doing translation work. The majority of the translation is done ahead of time, but as they are doing the work alongside their regular workload they sometimes don't finish a page all at once. These are typical non-tech-savvy users, so they're treating it like an open application.
I'm not sure of the exact timelines, but my guess is that when they have a page open for more than an hour before saving it it times out and they lose all the work. Now of course I have warned them, but it happens again here and there when they aren't paying attention.
My having started with the appropriate RTFM response, I did think it might be appropriate to drop a note in and ask if the timeout could be extended a bit? The reason I ask is that, while there may be some security benefit to enforcing a timeout, no compelling reason comes to mind to set a timeout at one hour versus two or three or even six (heh). Obviously, what I don't know about your strategy and performance tweaking would fill several rooms, but this would make things a bit easier on the actual workers handling translation as the work this client is doing is fairly extensive and the timeouts they're encountering somewhat understandable.
Still, not a serious issue, just something I thought worth mentioning if it doesn't impact any of your operations.
Great product and we're rolling right along using it (in 4-5 different languages with people from/in several countries)! Thanks again :)