Hi Yvaelle,
Have you tried updating to the 4.5.1 hotfix? Some Launcher issues were fixed with this release.
If that doesn’t work, please try the troubleshooting steps linked below. Afterwards, the next step would be to try reinstalling the Launcher.
If the issue still persist, please follow the instructions at the bottom of the link and post your ‘Verbose Logs’. They will help us track down the issue.
Thanks,
TJ