"The network path is not found"

If you're using an external source, be it a drive or a network, to access your image library. you might see this annoying error message when re-indexing a folder:

The [drive/network] is not accessible. The network path is not found."

Try this to resolve it: Test the folder several times. If the error message continues, just select the folder, got to Tools>Cache?purge cache for [folder name] selection and voila!