The black screen issue may be caused by different reasons by usually it's either "Host restart required" (after the installation, that is) or graphics card/drivers issue in which case the driver should be updated.
Is this OK; that is, is he telling me the correct ID?
Yes, the 12-digit IDs are now the current format. However, 9-digit IDs are also supported for backward compatibility. That is, you can still connect to older Host installations from newly updated Viewer.
Just realized that the "Check for Updates" button on my current version doesn't work! So manually downloaded and installed new version.
Automatic download of an update file was implemented only recently. That's why it's not available in version 6.3 and earlier.
P.S. We try to improve update-related features with each release. Now you can automatically update both Viewer and Hosts, meaning that you just need to click a button and the program will do the rest. This tutorial explains how, see "Updating Viewer Method 1" and "Updating Hosts Method 1".
Note that the word "automatic" here doesn't mean that the program updates on its own without the user's consent. It is the user who makes a decision and initiates the update process.
It is hard to figure out exactly what might be causing this behavior. I can only say that our team is going to revamp the code related to dragging and dropping and make it more robust and feature-rich.
I've at least got my internet ID connection working now so I'm back up and running. I'll work on getting the direct connection/WOL configured later this weekend when I've got some time.
By definition, direct connection is always better in terms of performance and speed. However, it requires doing some configuration on the Host side - especially when you connect between networks rather than within the same network. Specifically, you will need to create a port forwarding rule on the Host side.
From what you describe, it looks as if some program - a registry cleaner perhaps, an antivirus program or even Windows update - corrupted or deleted Host registry entry (key). The Host keeps all its settings, including Internet-ID connection settings in Windows registry, in this key:
Even when it works I have to wait a few seconds for the mouse cursor to change.
This is how it is supposed to work. You should allow the program 1-3 seconds before it receives a response from the Host and finish the operation. Performance usually depends on the kind of connection used - on a LAN it should be faster that when using the Internet-ID.