Hi nandoman89,
It’s ver unlikely that Avast Battery Saver is responsible for this problem if it still happens after the uninstall. It’s probably being caused by other app or a bug in the Android version that you are currently using. I advise you to try update the Android version you are using, if possible (this can be done in About phone - System Updates). If it doesn’t work, try reinstalling Avast Battery Saver, open the Smart Profile and change the Screen time-out setting, inside the profile, to 2 minutes. Let me know how it goes.