Had the EXACT same issue on mine, never unlocked or rooted. Sometimes the volume would just disappear as well (even when using headphones) but the Beats icon would still show. Everything would go into permanent landscape mode at times. Calls answered in speaker automatically. If I plugged it in while it was on I got the usb host notification. The car mode app thingamajig launched for no flippin' reason, had to turn it off to charge it, all that jazz.
Definitely a hardware issue with the usb port. I took mine to Sprint hoping for a replacement but it has a barely visible crack horizontally across the screen so that was denied unless I agreed to pay the $150 deductible. It flew out of a car with me about a month prior so that did some damage to the phone. Then I dropped it the day these issues started happening. The port felt loose, I figured all of the wear and tear messed it up.
I didn't actually fix the phone though. It just randomly started working smoothly again and I haven't had a problem with it since - it has been a couple of months now. From all of the research I did, I saw that most people had the problem just fix itself for no reason and never come back. I tried cleaning the port and poking and prodding but nothing fixed it. Just one day, BOOM, all better.
Hope it decides to behave soon
Sent from my HTCONE using Tapatalk 2
Hboot 2.02 S-Off
Amon Ra recovery
More stuff that I'm too lazy to figure out and type.
MIUI 2.3.2_b1 ES (by Swiperat)
Extended Settings Mod
Tiamat 4.1.0 SBC
My wallpaper collection
If you think I can help you with something or need me to elaborate on a post then feel free to pm me. I'll try my best to help you out.
Oh, and I have a vagina. Fear me :P