When I plug in a drive and goto its properties in DOpus, it doesn't load the drive's label. It doesn't show in the tree, or the properties dialog. Windows Explorer shows the label. If I change the label in DOpus, the changes are reflected in Windows Explorer immediately, but not in DOpus, even after an F5. Windows Explorer changes the label as normal, of course.
"When you plug in a drive"... meaning you only see this with external hot pluggable drives? What kind of drive are you seeing it with? I don't have an external USB or flash drive handy at the moment to test with... but I use both pretty frequently on Win7 x64 and I haven't noticed the problem myself so far.
Opus has nothing at all to do with the Properties dialog, except that Opus can cause the dialog to appear for a specified file/folder. The dialog itself is completely driven by the Windows shell.
The fact that the Properties dialog (as well as Opus itself) shows different names for the drive based on whether or not it is displayed by dopus.exe or explorer.exe suggests that something is treating Opus and the drive differently in some way, though I cannot think that that might be. (Maybe Opus is being run in some compatibility mode, but I can't think why that would have this effect.)
I don't know why something would allow drive properties to be read, but not list a drive label? DOpus isn't running in any compatibility mode that I know of.
I just tested with the internal drive, and it works normally on the internal drive. This issue only arises on USB drives, apparently.