I'm using 11.10.
I've created /usr/share/applications/idea.desktop with such content:
[Desktop Entry]
Name=IntellijIdea
Comment=Idea
Exec=idea
StartupNotify=true
Icon=/usr/java/idea-IU-107.587/bin/idea128.png
Terminal=false
Type=Application
Then I opened Dash and typed idea. I saw an icon and pressed it. The application started. I clicked with the right mouse button on its icon in the launcher and selected "keep in launcher". When I restarted my notebook, the icon disappeared from the launcher. Where can be the problem?