Apple has notified us that there is a crashing issue (and a no-sound issue) with bleep!BOX under iOS 4.0 – we are working hard to get this resolved as soon as possible. Until then, I would recommend not upgrading your phone to iOS 4.0 just yet, if using bleep!BOX is important to you.
We are still working hard to resolve these issues – we have a fix for the no-sound issue and are working out some OpenGL related issues on specific devices. I am hopeful that we will be able to submit a new update sometime this coming week. For now, stick to bleep!BOX on iOS 3.2 (iPad) or 3.1.3.