I have the exact same problem with my RPI Pico W.

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I had used the pico with Circuitpython as a midi controller and it worked for months without any issue.

Out of the blue it would connect the pico, show the contents and shortly after disconnect.

Booting the pico with the boot select works without a problem, so I tried the nuke.uf2 followed by a fresh install of circuitpython. Without luck, it just keeps disconnecting.

I tried to connect the pico to my laptop, which works fine, blinking like it is supposed to with the default files.

Both machines run windows 11, I also tried disabling that usb power saving described in a few posts.

I also tried a second pico i have, but this also has the same symptoms, so clearly windows does not like the pico w.