Well, @Geneviève Boisjoli, you can try doing another factory reset but I think that there may be some problem with the ROM, I would say much more better option will be backup up your data and reloading your device with stock ROM.
How to flash stock ROM over your device?
1) Make sure you have installed all the USB drivers in order to connect with the PC/Laptop
2) Make sure Enable USB Debugging Mode on tablet to connect it with the computer and use Android SDK with it. You can enable the USB debugging mode over, Navigate to** Settings>> About tablet, Tap on Build Number** several times until a message appears saying 'You are now a Developer.' Now go to Settings>> Developer Options to enable USB Debugging Mode.
3) Remember to make a backup of your data before proceeding as this is going to wipe out all your data.
4) Also make sure that your device is holding at least 80% of battery.
5) Remember the device will no longer belong to a rooted version with the installation of official firmware.
8) Get the appropriate *stock ROM for your device downloaded from Sammobile firmware section *
How to install Stock ROM iGalaxy Tab 2 10.1:
Step-1: Download the appropriate stock ROM for your Galaxy Tab 2 10.1 and save it on a folder.
Step-2: Extract the downloaded firmware zip using winrar or any other extracting tool to get a .tar.md5 file with few other files.
Step-3: Download the latest version of ODIN and extract it to get Odin3 vx.xx.exe.
Step-4: Switch off the device.
Step-5: Boot the device into Download Mode by pressing and holding Volume Down and Power buttons together until a Android robot appears with a warning triangle. Now press the Volume Up button to enter Download Mode.
Step-6: Run Odin3 vx.xx.exe as Administrator
Step-7: Connect the device with to computer using USB cable while it is in Download mode. Wait for some time until Odin detects the device. When the phone is connected successfully Added message will appear under Odin and the ID: COM box in Odin will turn light blue with COM port number, indicating successful connection
Note: If the Added message does not appear, then try to re-install USB derivers or change the USB port on the computer.
Step-8: Select these files extracted from the folder (the place you have extracted stock ROM) to install on the tablet
a) Click the PDA button and select the .tar.md5 file
b) Click the Phone button and select file with MODEM in its name
c) Click the CSC button and select file with CSC in its name
d) Click the PIT button and select the .pit file
Note: Ignore the last three steps (step-b, c and d) if such files do not exist.
Step-9: In Odin enable Auto Reboot and F.Reset Time checkboxes. Click the Re-Partition checkbox if a .pit file has been chosen in the previous step
Step-10: Verify everything and click the Start button in Odin. The installation process should begin now and take about few minutes to complete
Step-11: When the installation process is completed, the tablet will restart automatically and a PASS message with green background will appear. Unplug the USB cable from the phone
All done enjoy your device!
— modified on Nov 19, 2014, 6:59:37 AM