Re: omputer started up and then monitor turned off after 10-20 seconds
Yeah Technoman might have a point.
It could be the video drivers, being that they haven't installed correctly or something has happened with them or the resolution is too high for your monitor or something which can sometimes be set to change when you restart.
Safe mode will fix this like Technoman says, as you'll be able to reset settings or do a re-install of drivers
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