sorry to hear about yr problem f.stop, for yr application failed to launch (goes back to Home Screen), try the below solution. It's a known issue:
I searched over the web, this is happening to iPod Touch and iPhone after iTunes 7.7.1 is launched. Some what, a file call DRM is corrupted in the fone, where all iTunes installed pgm will crash upon loading.
DRM is a file related to iTunes licensing.
Apple is aware of this and they promised the fixes since last year but till today, it is still happening. Hope the OS3.0 will help.
Do not be overly worry as there's a quick solution for this. Simply download a small app from iTunes and install it, the damaged DRM file will be replaced and after that, ALL other iTunes apps will run again.
But then, it will re-occur again, no guarantee, especually u sync it with iTunes. Hope this info helps. Anyhow, I am loving the iPhone very much.
thanks bro... yup tats wat i hv been doing but still its kinda annoying especially like when i'm in oversea, whn certain application that I hv downloaded & need to use & it crash. sigh & whn thr are no wifi or anything for me to download that's a real pissed off.