This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
That's fine. In fact you don't need to prompt in any mode if you're able to use the previous settings, else prompt. You'll probably put the user in a sort of a loop unless you can reuse settings. It would attempt to initialise -> fail -> check if user wants to reconfigure settings -> attempt to initialise -> and so on until either successful or the user chooses to exit. As you said in the case of 'alone' the only cause for failure is the db not being there, it's possible so cater for that by catching the exception -> prompt to reconfigure settings etc.
I just always loaded the same settings screen, nothing special for just the missing database.