How to safely remove a USB drive when "Windows can't stop your 'Generic volume' device because a program is still using it."?

"Look for RemoveDrive on this page (direct link to the Drive Tools page RemoveDrive tool section).
Those pages also have good related information.

The RemoveDrive tool is useful also when
you Do not get ‘Safely remove’ option in Tray for USB storage devices."

"There are several reasons to USB being undismountable:

It's in use. Please note that if you're looking at the disk in Explorer, then it's in use!
Windows is finishing copying a big file to or from the disk (rarely the reason)
A bug in Windows causes conime.exe to get stuck on the disk (it may safely be killed)
If the USB drive is formatted as NTFS, the journal of all file updates may still be open
If disk indexing is on for the drive, Windows may be furiously indexing all files on it

My advice is to:

Make sure the USB drive is not defined as indexed.
Wait, and then try again. It might work a few seconds later on.
Buy Zentimo ($29.90) that does a good job of trying to remove the disk. Even if it fails, it still tells you which programs are using what files (I paid)."

"I found the free USB Disk Ejector to be very useful:

A program that allows you to quickly remove drives in Windows. It can eject USB disks, Firewire disks and memory cards. It is a quick, flexible, portable alternative to using Windows’ “Safely Remove Hardware” dialog."

If it's none of the pedestrian/common options, it could be you have the drive listed as 'shared' on a network and have accessed it via another computer. In my case, even though the remote computer was off, it still had a lock on the directories. Unshare and it should work if that's the case.

"Quick Way to Find Process/File Open that is Preventing Unmount:

I just figured this out. With Process Explorer (free download) this is really easy.

Download, unzip and run procexp.exe
Choose from the ""Find"" menu, ""Find Handle or DLL..."" or hit Cntl-F
Enter only the drive letter (followed by "":\"") in the search text box

This will show you all the open files on your removable volume, the processes that own the file handle and the PIDs of the processes. Double click to highlight the process in the main window (top) and file (bottom). From there you can right-click the process to kill it or right-click the file to close the file handle."