Can't remove one of my ext HDs in 7, but can in XP

Hi.

I have two external USB2 HDs. Whn I click on the Safely Remove HW tray in W7 Ult 64-bit, HD-1 is shown, and I can remove it, but HD-2 is not shown, and therefore I cant remove it.

But HD-2 does show on the Safely Remove HW tray in XP. Same computer, btw. Am I ok to just shut down the HD, or may I run into trouble by doing that? I learned the hard way a few years ago that you can't do that with drives attached to Mac OSX. Am I ok here? Any ideas why that HD would not show up in W7, when it does in XP?

Thanks in advance.

The Safely Remove is a precaution to avoid that incomplete write operations are cut off in the middle thus loosing data. If you wait 30 seconds after the last write opertion, you can disconnect it. That should be enough time to flush all buffers. If you do only read operations on this HD, there is no danger anyhow.