My Tablet has frozen at the lockscreen twice this week, help appreciated

I am getting a little concerned about my Nexus 7's performance lately. Every morning I bring it with me and listen to downloaded podcasts using the DoubleTwist Player app. I listen to them with Kinivo BTH220 Bluetooth headphones, it has a pause/play function that I use to hear other people with, using it dozens of times in a listen. I keep my N7 in a Bluerex slim case and it is shut and in sleep mode the whole time.

In the past week I have had the tablet freeze on me twice. It is working just fine, I pause the audio for a minute for whatever reason, then when I press unpause nothing happens. I then open up my case and the screen is frozen on the lock screen. I can still see where it shows pressing down on the unlock circle, but when I slide it out it stays frozen and just stays there. This forces me to hold down the power button to restart the tablet.

I have had this tablet since around thanksgiving time and the case and headphones I got for christmas. I have not had any problems like that until now, and twice in such a short time is worrying me. Any advice, help or suggestions would be most welcome at this time. Thank you.

If you haven't got a password or other security feature set why not disable the slide lock and see if that helps

I disabled the password to the lockscreen, started using the stock music app and turned off my live wallpaper. I though that fixed the problem until today. I was just using it listening to a saved podcast and after pausing for a few minutes when I pressed play to continue nothing happened. I turned on the N7 and it was sitting frozen in the app. After a few minutes I got a message that it stopped working and had to close. I closed it but then when I pressed the sleep/power button it went total black screen on me. I had to hold the power 30secs.

Any more suggestions?

something is making it crash, gonna be hard to pin point it, easiest way to correct it would be to back up any info you wanna keep and wipe it.