Screen goes off while playing and then the whole screen freezes

Glesni, I would suggest that you try to perform a hard reset. This will delete your data. Should your Galaxy Tab become unresponsive, you can perform a hard reset which will return the Galaxy Tab back to factory default settings.:"

1. Ensure your Galaxy Tab is switched off.

2. Press and hold the Volume Up button, then briefly press the Power button.

3. Release the Power button when the Samsung logo appears.

4. Wait for the boot menu to appear.

5. Use the Volume down button to navigate to wipe data/factory reset.

6. Press Home.

7. Highlight Yes -- delete all user data.

8. Press Home.

9. The Galaxy Tab will reboot."

from here. Hope this helps, good luck.