Cant unmount SanDisk extreme portable 250GB

Why do I consistently get the message that files are in use on my SSD and can not unmount it?

I thought this was an old relic issue with only older crappy usb/flashdrives? 

FYI:  no files are in use at all, the issue even occured before I had any files on it

Go to Finder > Application > Terminal and try “diskutil list”. Please note the name of your SanDisk.

Then type in “sudo diskutil unmountDisk disk1” (change disk1 to the volume of your drive). This will report back the named volume and location have been unmounted.

What is “finder”? 

Oh sorry, I thought you are using a Mac computer. 

Which OS is your computer running? Have you tested the issue in Safe Mode and Clean Boot

I suggest you check if there is any firmware update for your Seagate FreeAgent Go USB Drive first. You should also update the BIOS and motherboard to run Windows stably.

If the issue persists, I suggest you try to reinstall the USB Controllers to check the issue.