I have this problem all the time. I stopped bothering with safari and maps and pictures. I've taken all the advice and the problem is still there. I am on firmware 2.1, I've deleted any apps I've downloaded, I've cleared the cache, and finally restored the phone to original, nothing works.
Thing is, we probably both have defective phones. I work at best buy and if anyone bring in a phone like this, we'll just give them a new one. That is assuming that the customer is paying $15 a month for best buy insurance. Which is also stupid by the way. (Trust me I work there)