I have an unlocked iPhone 3G on 3.1.3. I used the Notes app for the first time yesterday (because I recently restored my iPhone, set it as a new phone, and started fresh). As I was writing, the app kept on crashing. At first it would be every like 6 minutes or so, then it slowly became more and more frequent, to the point of crashing every 10 seconds while I was trying to type.

I had no other apps running in the background, just the usual phone. SBSettings says my free memory was about ~50 MB. It happened last night, then I turned off my phone, went to bed, started it up this morning, and it started crashing again.

How can I fix this? It's very annoying.