hi, hope someone can help. My Toshiba satellite c50-b laptop has suddenly lost about 35gb from its normal 500gb. The shop is telling me this is due to a) Microsoft hiding the operating stem or b)'natural wastage'? I think this is lies but can't refute their claims. The disk management program does not show any hidden partitions. I only have the one c drive. I have been experimenting with Linux software but have removed them and tried resetting back to default and reinstalling window 10, but nothing gets me back to 500gb. Is this a problem with Toshiba hard disks? Hoping for any help.