If Windows Genuine Advantage from Microsoft Update Website detects that your Windows is not a genuine copy, the wallpaper will turn black automatically.
Either buy Windows, or activate it with your key.
My Computer
At a glance
Windows 7 UltimateAMD Athlon II X2 245 2.90Ghz3.00 GB8800GTS 512MB
Your desktop wallpaper will always return to black or stay black, and the (not genuine) watermark on the right side corner of your screen will also stay there, until you activate your copy of Windows 7.
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1XSamsung DVD burner SH-S223L/BEBN SATA
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