iPhone 3gs keeps flashing apple logo, tried switcing on and off, re-booting etc

Yesterday evening my phone sudeenly switched iteslf ff (which it has done occasionally) but when it comes back up it now shows a flashing apple log, and I can't re-boot?

I've done all the usual things - switch off for a while switch off and hold home and power buttons etc, but nothing is working. I have some notes on there which I updated on Friday and are essential for a ntaional magazine I write for, and don't want to lose them by doing a full restore, so anyone any good, easy suggestions?

Thanks guys............