I've connected my camera Canon Ixus 500 HS on my PC - get no drive letter however - but selected "My Computer" and can select the camera, select again and get the folders and files etc.
When I try to move the files, DO copies one file and ten DO tries to delete this file and I get "access denied".
When I copy all files and then delete them all works without problems.
When I use Windows Explorer, hold down the SHIFT key and move them to a drive letter in a Windows Explorer window, the move works.
I didn't install a driver for it. Device manager properties shows: Microsoft, 2006-06-21, 6.1.7600.16385.
If you can, plug the camera's memory card into a card reader/slot instead of connecting the camera itself via USB cable, as then you'll get a real drive/directory instead of a virtual folder.
Depending on the way the camera connects, we may have some improvements for what happens when you connect the camera itself in the future as part of the work on adding native MTP support to Opus.
I know that it works with the card reader but in my case I had to re-boot my PC because the card reader didn't detect the card - only after a re-boot. But the card reader also has an USB + eSata which will be detected after I've connect them. Mysterious.
That was the reason why I've connected via USB before re-boot.