Problems with iPhone applications closing abruptly

Since picking up my iPhone three days ago, I’ve been blown away by the UI and all the applications available for the phone. I’ve never had a phone that was so easy to use and so powerful at the same time.
My one gripe (and its a major one) is that applications frequently close up on me at random times for no reason. Texas Hold’Em is unplayable for me due to this glitch – it happens every time I play within minutes of getting started. Ditto with Super Monkey Ball. I was trying to review the latter just now and haven’t been able to since the game shuts down within minutes of opening the game. Is this a widespread issue? Are other iPhone 3G users seeing this?