Resposta parcial
Esta é uma cópia e colagem do fórum de suporte da HP sobre este assunto:
Was your video card built by AMD/ATI?
If so, the Vari-Bright feature must be on. To fix this go to:
1. AMD Vision Engine Control Center (or AMD Catalyst Control Center)
2. Power
3. PowerPlay
4. Uncheck the "Enable Vari-Bright" option.
and that will fix your problem.
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