Really hope someone can suggest something new? I have a Surface Pro 3 i5 running Win10 - all up to date. I recently purchased a Lexar microSDxc 128GB card (a very fast one 633x) from amazon.co.uk Popping it into the machine it appeared as I'd have expected and then a minute or two later just simply disappeared (not just from Explorer, but from the Disk Management interface - and from the Device Manager too). I've so far tried the following (as recommended in various posts across the web): A different card (I have a 256mb card from a long time ago) Uninstalling/deleting the existing driver and allowing Win to install a generic one (which I've done and it's still there) - as per the well-known reddit post Part removing the card from the socket Taking the card and formatting on my desktop to NTFS and doing it with a full (not quick) format ...but nothing helps. Every time I put it in, I get the same behaviour - all fine for a minute or two, then simply disappears. If it's a dud Pro 3 I'm a bit stuffed since it's out of warranty (I've never had need to use that slot before) - but there do seem to be an awful lot of people out there with something like this problem - anything I'm missing? I'd really appreciate any insights or suggestions.