My ipad4 behaving strangely since last week

Hi all,
I have an iPad4 which was working perfectly fine so far. From last week onwards it was behaving strange.
Sometimes screen gets stuck. If display comes, it will not allow me to open applications and sometimes The apps getting stuck. I have tried to restore this to factory settings and DFU mode, etc., but no luck.
What might be the problem with that? Is this happening because of the display/hardware issue or iOS issue? Can somebody help me resolve this issue please? Thanks in advance for any kind of help!
