My apps close immediately after opening them.

I have been having this problem for a while. It's already updated to the latest version for 2nd gen, v4.2.1, I tried rebooting, and I tried updating the apps. Still it runs slows and whenever I open a foreign (as in downloaded, not default with the device) app, it will begin to open for a few seconds then close immediately and bring me back to the home apps screen. I really need to figure this out cuz I can't use any of my apps now. Any suggestions?