NotifyLink Active Solution:

Behavior
My BlackBerry device keeps displaying a low memory alert.

Information
When available memory drops below 2MB during sending/receiving, an alert tone sounds and a dialog displays stating how much memory needs to be cleaned up.  In order for NotifyLink/NotifySync to run properly, the device must have at least 2MB of available space.  Prior to the dialog appearing, a low memory cleanup routine runs on the device in an attempt to rectify the problem.  So, if you keep seeing the dialog, the device has done all it can on its own and you are probably at a point where you need to free up some space. 

Solution
Free up some space by eliminating what you are not actively using. You can do this by:
 - cleaning up old data and turning on your clean-up options from the Notify Preferences menu
 - removing unnecessary applications or language packs
 - archiving data (such as attachments, pictures, custom ringtones, etc.) to the SD card storage

Sending/receiving will not continue until there is at least 2MB of free memory.