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You may need to back up all data of yours that is stored on the Android handheld device in question, to another device - either Synced to a computer, or better, copied individually to a memory card and then the memory card taken out.
Then you might find the problem relieved by doing a Hard Reset (accompanied by a Data Wipe) on your Android device. This will erase all individual configurations and data on it back to factory-release condition. That might cure the problem.
(Also you might want to check for vulnerability in your Android OS. Android handhelds have been targets for hacking and malicious interference at a distance for some time now owing to published security holes - that, if still present, need patching.)