Make a repair or system restore using your Windows 7 DVD installer. Boot from CD, select your language, select Repair your computer, select Use the recovery tool to fix problems starting Windows, select your OS, try first start-up repair and afterwards log-in to windows. If it doesn't fix your problem. Boot again from CD but this time select System Restore instead of start-up repair. Select restore point before the error happened.
so funny story, the other day I was smoking outside my house during a storm and I saw an electric box-thing on the size of my house spark up. so I ran inside and saw that the lights were off... then flickered back on. I thought, okay, I had a power-out and got to see what it looks like, cool. Came upstairs and my computer had a black screen, so I gave it a reboot ... and a few more. Wallpapers on my desktop do not show up, except sometimes when I hover over the "show desktop" button on the taskbar, and when programs shift views, ie for a game or video. not sure how a power-out could accomplish that, but I don't know how else it could have happened. eh?

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