I'm about to return my iPhone 3G (as I'm still within the 14 day cool-off period). Before I go, I thought I'd leave my 2 cents worth here in case it helps prevent others from making the same mistake I did.
In a nutshell, the iPhone has at least two fundamental and very serious bugs. Once you hit one of these bugs, it seems there is no long term solution for getting out of them. Apple simply haven't provided a hard enough "reset", or a complete enough "restore from backup". Sooner or later you will hit one these bugs (in my case I hit them both within 48 hours). Then you will start perusing forums like this, whereupon you will find post after post of people with exactly your problem describing various laborious and purely circumstantial "solutions" that "seemed to work for them". It's a classic case of superstition reinforcement as demonstrated in pigeons in 1948 by B F Skinner:
http://www.crystalinks.com/skinner.html
The bugs for which nobody but Apple could possibly have an answer are:
1. All of your installed 3rd Party Apps will suddenly stop working. They will start, then quickly crash without any error message and return to the Home screen. You will then have to reinstall all of them to allow you to use them briefly until the next time this happens.
2. You iPhone will suddenly start refusing to connect to WiFi networks that it used to connect to just fine. No matter how many times you type in the correct password over and over again, or change settings you shouldn't have to change, or ask it to forget the network and start again, you will never, ever solve this in the long run. Again, there's a fundamental bug whereby the iPhone is "remembering" some faulty information, and there doesn't seem to be a way of ever correcting this faulty information.
By all accounts, there is little real evidence that Apple are even aware of either of these problems let alone endeavouring to fix them. Despite the fact that people have been "reporting" them for several months.
In a nutshell, the iPhone has at least two fundamental and very serious bugs. Once you hit one of these bugs, it seems there is no long term solution for getting out of them. Apple simply haven't provided a hard enough "reset", or a complete enough "restore from backup". Sooner or later you will hit one these bugs (in my case I hit them both within 48 hours). Then you will start perusing forums like this, whereupon you will find post after post of people with exactly your problem describing various laborious and purely circumstantial "solutions" that "seemed to work for them". It's a classic case of superstition reinforcement as demonstrated in pigeons in 1948 by B F Skinner:
http://www.crystalinks.com/skinner.html
The bugs for which nobody but Apple could possibly have an answer are:
1. All of your installed 3rd Party Apps will suddenly stop working. They will start, then quickly crash without any error message and return to the Home screen. You will then have to reinstall all of them to allow you to use them briefly until the next time this happens.
2. You iPhone will suddenly start refusing to connect to WiFi networks that it used to connect to just fine. No matter how many times you type in the correct password over and over again, or change settings you shouldn't have to change, or ask it to forget the network and start again, you will never, ever solve this in the long run. Again, there's a fundamental bug whereby the iPhone is "remembering" some faulty information, and there doesn't seem to be a way of ever correcting this faulty information.
By all accounts, there is little real evidence that Apple are even aware of either of these problems let alone endeavouring to fix them. Despite the fact that people have been "reporting" them for several months.