[Q] Lollipop bug on USB conection topic

When I connect my device on the computer, the lockscreen is unlocked, but when I try to access the device's folders on my computer, nothing appears, and when I open some app and later I press the home button, the screen goes black (but the Virtual Android Buttons still appears) even when I press some button, the black screen don't disappears and only way to fix is restarting, but when is started, the date/hour are outdated

This sometimes happens

How can I fix this?
My device is the XT1069

Sorry for my bad english