On my 8830, there is an icon that looks like a crosshair at the upper left of the status bar (the bar that contains the date/time, new message indicator, etc.). It's located just under the signal strength bars.
I too had this icon for several days. Finally figured it out! The "mystery icon" a circle with a line through it and a number located next it is a BB app world update! Go to BB app world on your device and you will see the update. I hope this helps ease some minds.