September 30th, 2012, 01:45 PM
Join Date: Aug 2011
Carrier: Not Provided
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Never had such problem, if its just a system glitch rebooting the phone should solve it.
If that doesn't works see if you installed any app that controls the brightness, maybe its causing the problem.
You can try a factory reset as the next option, it will erase all your phone data, make a backup through MyBackup app before doing it.
If nothing works, it must be a hardware problem, take it to the service center.
Samsung GT-S5830 Galaxy Ace
ROM: AOKP 4.2.2
Scripts: CronMod INT2EXT4+
245MHz - 800MHz, SmartassH3