Systems Support Specialist
Sounds like you have set them to archive.. It's nothing exciting, just means that as you havnt used the files in a while the system has automatically archived them.
They should still be available as normal..
If you would rather it didn't do it (not sure why you wouldn't want it) you can right click on the drive and click properties, then switch it off.
Can't provide exact description, as I use Linux and not Windows.
Seriously though - it's nothing to worry about
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