Re: Application management memory too low
First of all, if you have a "9900B" you most likely have a Chinese-made knockoff and NOT a real BlackBerry. If that's the case, there is nothing for it but to bin the counterfeit device and get a real one.
If you have a legit BlackBerry, make sure all your photos/ringtones/videos/music are on your storage card instead of in the internal memory. You can also delete the browser cache on your device. Over time the cache can grow and eat up precious memory.
The Bold Touch 9900 comes with 8GB of internal storage plus 768MB of RAM. It's that RAM internal memory where all your downloaded apps are stored, plus any associated data bases they create. The internal RAM is also the memory the device uses for the operating system. You need at least 15MB of free memory for the device to work as it's supposed to. That's a *bare minimum* number though, and you will probably see a performance hit long before you reach that minimum.