I have Verizon.

My phone won't alert me when I get a text message. Sometimes I check my phone for the time or just to check, and I'll notice it'll say '1 unread text message' it'll also start ringing to alert me. The timestamp is accurate to when the text was sent, but my phone isn't telling me it's there. If I get a second (or a phone call) this usually flushes it out and it'll ring/beep.

I've also noticed a similar snag on getting phone calls. Sometimes It'll start ringing, but pretty much be frozen for a couple of seconds so that I can't answer the phone. I've missed calls because of this.

After a couple of customer service calls I made Verizon replace the phone. But I appear to be having the same problems. Anyone have any idea on this? I'm starting to think it might be related to running custom ringtones off the SD card. Maybe when the phone 'sleeps' it shuts off the card?