I’ve not had anything back from Apple yet but trawling through discussions this afternoon it looks like others with similar problems have been told it’s an iTunes fault. The latest iTunes update seemingly ‘split’ some people’s iTunes account, losing their old purchases and hence meaning an app authenticating itself will fail.

2.0.1 has been working fine for the last couple of days and certainly seems more stable with the free app’s that I’ve downloaded again. I don’t blame you for hanging fire on upgrading though.