[PatrickFallon]

Hi whpalmer4, thanks for all the info.
Yep there are a tonne of crash reports in there (about 20 each of "OmniFocus-r114082_2009-07-28-092509_Patrick-Fallons-iPhone" and "OmniFocus-r114082_2009-07-28-092509_Patrick-Fallons-iPhone"). None of them start with "low memory".

Re Bluetooth, I am not an IT expert, although I am reasonably proficient with Macs. However it does seem to me from my experiences (and the experiences of others online) the problem is caused whenever the iPhone/Mac wireless network changes. If I was able to use Bluetooth I would always be syncing between my Mac and my iPhone via the same Bluetooth connection so a change in wireless networks should have no effect.
That's one reason why I can't help but think Bluetooth might have been a better option for syncing. Whatever, simply put at the moment I am spending more time trying to solve sync failures than I am successfully syncing.

"I'm thinking that the reason you get the sync failures is that your iPhone and Mac aren't on the same network, and thus can't find each other. If the Mac's network gets changed, you have to change the settings on the iPhone to join that network or it won't be able to sync".

This is stating the obvious, the Mac and the iPhone are always on the same network. I have two wireless networks at home, but I always use the same one for both the Mac and the iPhone. And yes I check the Mac and iPhone havent' automatically connected to the other network for some reason. I am always syncing (or rather trying to sync) the iPhone and Mac at home on the same network. I am aware that changing networks (ie when going on a wireless network on either iPhone or Mac when out and about) causes syncing issues and I have been quitting OF on the mac and iPhone and retrying (as per Brian's suggestion). this sometimes works, sometimes doesn't. Likewise creating a a computer to iPhone network sometimes works sometimes doesnt. Cheers, Patrick