Windows 7: Notification area issues

In my notification area (by the time) I have three objects: Sound controls, internet, and Action Center. By clicking on the arrow next to it you see a tray of many other things that I like to keep out of sight. However, often one of these items (For example, Dropbox) will randomly hop out of the tray and into the list with the other three objects and will be in clear sight. It is not just Dropbox that does it (although that seems to be the usual perp), so I don't believe it has something to do with Dropbox connecting all the time or being "active". Is there any solution to this problem? I have tried going into the properties of the notification area ("Customize...") and turning the icons off, but to no avail.

Just 'grab' it and stick it back into the box.

I've tried that, and it'll work for a time, but it hops out randomly.

Edit: Also, it's worth nothing that I am often not even able to "grab" it, for as soon as I click it, it disappears and is in the box.