Windows 7 USB External Hard Drive Detected But Not In Explorer

In the disk manager does the drive have a letter and is it online?
Joe

Drive shows in Disk Manager as type Dynamic, and status of Invalid, with no drive letter. Right-click => Reactivate brings the error message "The operation is not allowed on the invalid disk pack."

I've got a very similar problem to Ambaldan, and looking through this forum it seems we're not alone having issues with external HDDs in Windows 7.

I'm using Window 7 64bit, on my brand new Toshiba laptop. I have tried to connect my LaCie 250GB hard drive but it fails to appear in the list of drives in the "Computer" section.

So far I have checked the following

1) that it works on another PC, which it does without any issues, although this was Vista not Win 7

2) that it appears in the device manager, which it does. No driver issues or the like are indicated

3) In diskmgmt.msc, the device appears as "Disk 1; Basic; 230GB; Online" in the bottom portion of the Disk Management window, however it does NOT appear in the list of drives in the top portion of the window.
When I tried to assign a drive letter to the external HDD, an error message stating that the console view has not been refreshed occurred, and is not sorted out by refreshing the view, nor by restarting the computer.

Any ideas?

-Will

Hi Joe,

Yes, it is listed as online. This is what my disk management screen looks like when I try to assign a drive letter. Refreshing the console and restarting the computer don't solve the problem.

The drive in question is Disk 2 in this screenshot.