So I updated to 3.1 had this issue last night after my iphone had been sitting idle. The screen wouldn't come back up even after I had hit the home button clearly it was off but I hadn't turned it off. Held the sleep wake button for 3 seconds nothing (as it normally turns the iPhone on like that with no problem) I had to hold the home button and power button for 10-15 seconds (like a hard reset) to get it to come back up. I didn't think too much of it because I had just restored (had been jailbroken 3G 8GB) and it had been syncing and updating for awhile. But today it did the same thing I had used it slid it into my pocket pulled it back out two minutes later to bring up something on it. BOOM again with the whole screen being out. Anyone else having this issue?