I worked through this together with Claude AI, and parts of this post are based on a summarized version of that process. I am posting this because I found help on forums and I want to give back and archive a solution online.
I recently got a second-hand OP-1 in mint condition and ran into the classic Windows disk mode freezing issue. The drive would show up with a drive letter, but opening it in Explorer caused an endless spinning circle. I could briefly access the first folder layer if I was fast enough, but any deeper interaction froze everything.
What we initially tried (none of which fully solved it):
- Disabling USB Selective Suspend, AutoPlay, and Windows Indexing
- Using a USB 2.0 hub (didn’t help — not a bandwidth issue)
- Third-party file managers like FreeCommander — also froze
- Robocopy via command line — also stalled
- A custom Python script with deliberate slow reads and retries — partially worked, but unreliable
The breakthrough — Wireshark USB sniffing
Instead of guessing, we installed Wireshark with USBPcap and monitored the USB traffic between the PC and the OP-1 using the filter:
usb.device_address == [device number]
At the exact moment the OP-1 froze, Wireshark showed:
SCSI command 0x85 — ATA PASS-THROUGH
ATA command 0xEC — IDENTIFY DEVICE
This is a command typically used by storage monitoring software to query drive health/SMART data.
The OP-1 does not support ATA commands, so it does not respond. Windows then waits for a response that never comes, which causes Explorer to freeze.
Finding the process sending the ATA command
Running this in an elevated Command Prompt while the OP-1 was connected:
sc query type= driver state= running | findstr /i “disk storage ata smart”
This identified Samsung Magician (SamsungMagicianSVC) as the culprit in my case.
It was scanning all connected storage devices—including the OP-1—and sending ATA monitoring commands.
The fix
Stop the Samsung Magician service:
sc stop SamsungMagicianSVC
The OP-1 worked immediately—no workarounds needed. Just plug in and open it in Explorer like a normal drive.
Key takeaway
Samsung Magician was the cause in my case, but the underlying issue is broader:
Any storage/SSD monitoring software that sends ATA commands to all connected devices can cause this behavior.
Other possible culprits:
- Intel Rapid Storage Technology (IAStorDataMgrSvc, RstMwService)
- Other SMART / disk monitoring tools
Wireshark with USBPcap is extremely useful — it lets you see the exact moment and type of command that causes the freeze. Use AI to interpret the data. I hope this helps someone one day.