Hey guys, I've recently switched to OSX and discovered the exact same problem. I could replicate this problem on 2 separate machines running 10.8.2.
I just wanted to share my experiences with everyone and my discoveries.
Firstly, I can say with almost complete confidence that this has nothing to do with Dropbox. I cleared my Favourites, fully uninstalled Dropbox and could still reproduce the problem.
So here's my theory and workaround:
- This problem occurs when you are adding a favourite to your sidebar which resides on a non-OS drive
- It has nothing to do with whether or not the folder has a related symlink or not
- The problem seems to be triggered when some aspect of the folder changes which triggers the sidebar to update
The 3rd point is one of most importance. I kept wondering why I couldn't reproduce the issue while testing and as soon as I went ahead and updated the icon on one of the folders, BAM the drive appeared. Similarly, the same occurred when renaming the folder.
So here's my workaround, albiet not the best:
- Setup the folders you want to include in your Favourites with the appropriate icon and name
- Remove the existing favourites relating to those folders
- You may run killall Finder from Terminal at this point to be sure that nothing comes back
- Re-add all your folders to favourites
- DO NOT rename them or modify their icon, if you do wish to do that, you'll need to repeat this process again
Based on my initial testing, this did the trick, but I'll be trying it out over the next week and will let you know how it goes.
As far as I can tell, the only triggers are icon and name changes but there could obviously be more, hopefully not though ...
I must say that OSX's handling of external drives and symlinks is buggy and hugely problematic. Here are some more workarounds to problems I found:
- Boring Folder Icons in Favourites: Enable colour icons in XtraFinder or install the SideEffects
- Wallpaper Reverting to Default: Don't store your wallpapers on a non-OS drive
If there are any more gotchas that I have missed, please let me know.
Hope this helps someone out there

zambz