I recently installed Rosegarden. When it had ran for the first time, it worked excellent. After, I had to restart my computer and when I ran it for the second time, something strange was occurred: according to the System Monitor, Rosegarden was running, in spite of I couldn't see the application, sometimes it's opened at other desktop and also Unity always has some instability problems like disappear the title bar of other programs or a zone is marked (for example, when we drag a window to the right side, we can see an "orange" area and the window's size is reduced to distribute at the middle of the desktop) at the left side of the screen and isn't hidden.
Maybe deleting your metadata would help? See this answer for more details.
I'd put this in a comment If I could.