I am having a problem with Windows 7 x64 consistently disconnecting one specific USB mass storage drive immediately after it is connected. The drive in question is a Cowon C2 digital music player which works in standard mass storage controller mode (i.e. no device-specific drivers needed/available).

When I connect the player, Windows plays the "USB connect" sound and the device appears (under its correct name) in the device manager, but it never appears as a drive. The player itself displays "USB Connected" for a split-second before reporting that it has been disconnected again. Since the player, by design, reboots after it has been disconnected, Windows plays the "USB disconnect" sound before restarting the whole cycle once the player has powered back on.

I am connecting the player through an Intel X79 Chipset motherboard (Gigabyte GA-X79-UD3) to Windows 7 Pro 64-bit. The player used to work fine the first few times I connected it, showing up as an external drive; it only recently stopped working. It is not a problem with the player, since it works fine when connected to another computer, even such running the exact same operating system. It is also not a problem with the USB controller, since the issue is the same on both the Intel USB 2.0 and the Fresco Logic FL1009 USB 3.0 controller ports. I have also not had the problem with any other drive so far.

Among the things I have tried so far:

• Disabling USB legacy mode in BIOS
• Disabling energy-saving power down for all USB controllers in Windows' device manager
• Removing and reinstalling Windows' USB mass storage driver
• Removing and reinstalling Intel and Fresco Logic USB controller driver
• Restoring the player to factory defaults

None of these made a difference. Again, the player used to work fine on the exact same system just days ago; I didn't install any new hardware or drivers on it since then. I would be very grateful for any hints on what else to try.

Edit: Here is another new hint; I found out that when I connect the drive before booting Windows, it is available in Windows Explorer as it should, and does not automatically disconnect. If I remove and reconnect it though, the infinite connect/disconnect-loop starts anew.