hi!
I have dove nothing but removing app, and install another.
The rebooting was slowly than usually, and after it finished - it all became very slowly, and not responding. It even pop a message about "Not Responding" after I waited a while.
What to do??

Do a hard reset. That is, with the power on, remove the battery for at least 30 seconds. Go ahead and keep the battery out a good minute or two this time. Then test.