I've tried installing several applications using Installer.app. Namely, lights out, NES, and iFlashCard. All three installed without any errors, and show up in Springboard. But when I try to execute them, their "window" opens very briefly (without any contents), then I'm immediately returned back to Springboard.

I installed the BSD Subsystem and OpenSSH via Installer.app, and have no problems with those tools.

I also installed Summerboard via Installer.app, and am not having any problems with that. However, I'm assuming it's not an independent executable, and only a modifcation of Springboard.

I previously installed MobileFinder via sftp, and it launches perfectly fine.

So it seems to be only .app bundles that are installed via Installer.app

Any ideas?