Sounds like a memory issue. Go to Options > Status > File Free. Anything less than 10mb (10,000,000 bytes) is on the low end of the scale. The Pearl is also known to have some memory leaks. Make sure you have the latest OS version installed on it.
As for the BB Messenger message, this is normal. It's not a text message area as a general message inbox. Text messages and emails are also logged in this area.
