While streaming soccer last night, my old Vista-running Acer Aspire 5520 shut down without warning. This has happened before, but I attributed it to dust and blew into the fan and it tended to do the trick. When the battery was in and this happened, at least the green power light blinks first, along with the orange battery light, giving me a little warning to save my work. This time, I opened the bottom, removed and took apart the fan to clean out the dust, removed the heat sink and thoroughly unclogged and cleaned the vent combs/fins (they were quite bad) and applied Noctua thermal paste in two spots where there had been some crusty paste before (I followed a Youtube tutorial). Alas, it still shuts down after a minute or so, after booting up fine and getting to the desktop. I can hear the fan. I tried the trick where you hold the power button down for 30 secs without battery or adapter plugged in, and after this, the orange battery light no longer blinks, but if I turn the computer on it shuts off again soon after (I can hear the fan). Thanks!