I keep getting this problem with BBM !
Sometime (quite often) I find that the volume of BBM is really low compared to other applications and I recently found out what it was by looking at the volume control Mixer down at the system tray where you can adjust all audio devices.
Somehow BBM has lowered itself and I have to put it back to max !
Really annoying !
Windows 7 Ultimate SP1 - 64bit
See attached image !