To ensure that the file is visible on the network, perhaps it could be accessed by the client ie. 10 seconds before it should be visible? This should ensure that Windows has the path cached, right?The change i'm making is to create the next timeshifting file before the previous one is completely filled. This should allow plenty of time for the next file to be ready on the network share before it is needed.
At the moment a new file is only created the instant the previous one is completely filled and (i'm guessing) it sometimes takes a little while to be 'seen' on the share which is why it sometimes fails to open.
Maybe this is already your idea