Two apps (NYTimes and NPR Player) stopped working on one of my two iphone 3G's: the app logo comes up, then it's back to the home screen. One of these apps (NYTimes) was recently updated, so I figured I'd go back to an earlier version. I was able to retrieve the .ipa file from the recycle bin, put it in the folder with the other apps, "hid" the recent version (after having de-installed it from the phone), but I can't seem to be able to fool iTunes into installing it on the phone. I guess somewhere it knows what the latest version is, and won't accept any substitutes.
My other 3G is identically configured but it can (still) run these two apps. I know it's an old model, but it's still useful. My "main" phones are two 4S's.