Why does the Mac OS X firewall dialog recurringly pop-up and disappear by itself (without letting me respond) under Snow Leopard?

Problem

From time to time, I'll be on my Macbook using a program that accesses the network – whether Firefox, or Sony's Reader Library – really, it seems like it could happen with any program that accesses the network – and for no reason that I can discern so far (that is, it happens intermittently) the OS X firewall dialog pops up to ask me the question: [OS X firewall dialog] Do you want the application "Reader Library.app" to accept incoming network connections? Clicking Deny may limit the application's behavior. This setting can be changed in the Firewall pane of Security preferences. [Deny] [Allow] Except it doesn't actually let me click anything before it disappears! That is: the dialog pops up, ... then goes away by itself a second later, then pops up again, ... then goes away by itself a second later, etc. It happens a few times before stopping. It wouldn't be so maddening to be interrupted if I could just be allowed to click "Allow" and make the darn thing go away for good. In Securi…