Battery Related Problem...?

Over the past few days I've been conditioning the battery on my iPhone to make sure that isn't the cause of this....

I'll go throughout my whole day, the phone gets down to 20%, yeah yeah, normal. I'll send a few txt messages, push the sleep button and let the screen turn off (no, not turn the phone off).

I check about 5 minutes later, click the home button. I have no service (one bar without an edge, grps, 3g, or wifi icon, but AT&T displayed), the battery is no longer on 20% (it switches up to 1/3 of the way sometimes, 1/4 sometimes, 1/5 sometimes), and the slide to unlock button freezes up for 5+ seconds.

I slide my finger across, wait the 5 seconds or so, and the phone goes to the home screen. All of a sudden (as the phone regains service) I'll receive any txt messages that have been sent to me since the last time the phone decided to randomly go out of service.

I've restored the phone, used it until it won't turn on anymore (completely dead), conditioned it multiple times....

Any tips on what's going on? Should I take it to the apple store?