I'm still pondering this. It's a bit of a puzzler this one. Using Dreamweaver, can you still access a document in your other 'working' site, and make a change without getting an error?
If you can, perhaps you should try putting one of your 'starting point' folders in the same directory that your working site folders and files are in and make sure that you can edit them there ok, - just to test.
If the edit 'takes', then we really need to know what the difference between your two set-ups might be, or duplicate your working one. Was your other site an all-html site, or did you have dynamic (php) pages in it?
At the moment, I can't even think of the right questions, let alone any possible answers.
I'll have a think, and in the mean time hopefully someone will jump in with the logical obvious solution!
Will check in tomorrow.