F5 problems

Could anybody tell me why my acer laptop won't start working when I turn it on until I press the F5 key also it doesn't seem to remember some webpage setting I change, ie when I go back to to a page I've changed earlier, it's back to how it was before, it all started a few weeks back, when it failed to update, I have tried restoreing it, but nothing seems to work. :D
 
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