I recently discovered a case where Unix permissions had messed up what I wished to do with a project. For some reason the VIDEO_TS folder itself was marked read-only. (I have no idea how that happened, what with transferring files over the network, copying DVD mounted images to the hard drive, etc.
If such a situation arises, you will not be able to delete or replace any files in the folder, using the import/replace functions, so the operation will quit in the middle with a write permissions error and the VIDEO_TS folder will be left in an intermediate state.
In a future release we will check the permissions of the VIDEO_TS folder and its enclosing folder in addition to the checks now made on the individual files for the warning "Some files are not writable.... etc.", and will not permit the above operations which would fail. In the meantime, please be careful.