i chose the 'find missing regions manually' option from the prompt at project launch, and it found them where they were supposed to be - in the project folder - and reactivated them. no word from the apple guys on any of this. many thanks to the moderators for prompt response.

Hi noidea, Thanks! I'm sorry I wasn't clearer in my earlier posts. I thought you'd already searched for the "missing files" manually. This is the first course of action to take. Thanks for posting the solution / workaround. Cheers Rounik