I've been combating a problem with this for a few weeks now, and am unable to fix it on my own, which annoys me. I have my Surface Pro on all day at work, and use it as an additional computer. A lot of times I'll keep a log, for instance, in word on the SP so I don't have to switch on my main computer at work. The problem is, the SP will sporadically refuse to stay on for more than around 2 minutes. Randomly, and less than I'd be ok with, it will stay open, but 90% of the time it won't. I've changed the power plan to high performance, changed the settings both when you click it and in advanced/more power options to never shut off while on external power, and it still ignores me. Yesterday, turning off automatic brightness control fixed it, but it's flared up since then. I have no clue what to do but it's annoying and I need to stop it. Thanks!