If you want to clean the memory, best thing to do is a battery pull. Like blueberry mentioned above, you really need to pay close attention to the file free memory. You'll need at least 10MB for the BB to operate properly.
that number is close to the 12 that you need to not lose call logs and such. so with normal use you could drop below that number and then it will come back up when you do a reset. follow the memory link in my sig it will bring that number way up. when i had my pearl i had over 30mb of free space
