you're low on memory go to options/status and look at your file free if it's under 12,xxx,xxx bytes you will start to lose call logs and texts to free up space take a look at the memory link in my sig it will help you out
This is due to low memory on your BB. Go to Options>Status>File Free. Here you need at least 12,000,000 bytes of file free memory. If you are below this amount, follow instructions on this thread: http://forums.crackberry.com/f3/how-...-memory-34633/
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