I have just read [url]Insert CD Notification!] and at first I just wanted to answer there but then I saw that thread is pretty old so here's a new one, also because my approach on a solution to the topic is different.
I was searching for a way to disable the "insert disk" popup, too. It annoys me me to be forced to cancel a window only because I have once more managed to accidently click on the A: drive in the folder tree. My idea is NOT to hide the drive from the folder tree but to change the modal behaviour of the popup.
The changes in the Mozilla browsers regarding information about unreachable servers may serve as an example: In older versions Mozilla already had tabbed browsing and when I openend a few tabs then I might get some "unreachable" popup a few seconds later right in the middle of reading another tab => hate this! Later in Firefox this was changed: Now unreachable servers produce a "server unreachable" webpage in the corresponding tab => I will see it when I get there.
I think Opus should handle the "insert disk" notification in a similar way, by putting an informative "no disk inserted/this path is not available" message inside the respective lister (putting non-file-content inside listers is also done with the blue waiting wheel and the cancel button next to it). This is also the way to go for unavailable windows shares (type "\WrongComputername" into the address bar and wait) because this way the user isn't abruptly disturbed in his work.