Got my iPhone 4 today. Synced it up. Installed a Zagg shield. Everything was good. Then about 3 hours later at random I called my gf and tossed her on speakerphone and she couldn't hear me and I couldn't hear her. The entire unit on the bottom of the phone (mic+speaker) wasn't working. This persisted all day. I tried the old plug the headphones in and out a bunch of times trick. Didn't seem to be the problem. I did a bunch of hard resets...didn't work. Did a complete factory restore by plugging it back into my laptop...didn't work. Made a genius bar appointment. Started to go to bed. Plugged it into the wall and bam...the speaker+mike are working again. Any thoughts on this? Has anyone heard of this bug before? Should I try to return it and get another one or just count my blessings and be happy it is working again? EDIT: Just realized I might have been unclear. I made calls earlier in the day on speaker phone fine. When the unit went out I couldn't get any sound at all. No ringing, no keyboard typing noise, nothing. I could make calls without being on speaker phone as normal after the bottom speaker went out, and vibrate worked fine.