I recently installed Linux Mint 15 with Cinnamon. It ran smoothly after forcing a kernel update by activating visibility of "Level 5" "dangerous packages". Later, after a post-update reboot, my notifications look like those seen in Ubuntu's Unity (Notify OSD). I have only installed things through Mint's software center or apt-get.
It doesn't seem like the notifications stack up in the taskbar applet either. I do get the ubuntu styled notifications by triggering them with notify-send. The ubuntu styled notifications also replaces the volume up/down as well as brightness up/down notifications.
How can I debug this?