what is the version of Desktop Manager you are using? I recommend using 4.6 along with the 4.5 OS. By the way what build are you loading to your cell phone? You can try 188.8.131.52. By far it looks to be pretty stable with less memory leak.
1) Install the latest DM 4.6 (Available for download at the BlackBerry website)
2) Install the latest OS (http://www.blackberryforums.com/gene...languages.html
3) Follow the instructions to wipe the handset and reinstall the OS.