I'm not sure why I hadn't thought to try that through Tv itself I don't know if I could have solved it without going to the remote machine, but hopefully that is helpful to anyone else with this problem. What ended up resolving the issue was pressing ctrl-alt-del on the remote machine to bring up the help/lock screen, and that was it! Just from that, I regained full control both locally and remotely. Turns out, I had no input control on that machine - not keyboard or mouse - even when I had ended the Tv session. In my case, I use Tv as a mere lazy convenience to access a machine in another room of my house so, after discovering this issue, I just decided to see if there was anything wrong on the remote machine itself. I tried checking through multiple options, particularly 'disable remote input', and nothing worked. I just ran into a similar problem a few minutes ago: I could interact with the remote machine with my mouse, but all keyboard input remained inactive (this is the first time I have experienced this issue with Teamviewer). If Scroll Lock is OFF - Viewer Shortcuts ARE ENABLED (Grey) in the top right of the Viewer window (arrow icon pointing down).

Please note that Viewer Shortcuts need to be active to use keyboard shortcuts. TeamViewer is free for personal use, even over the Internet, but businesses have to pay. For speed, I love Splashtop, but there is a fee to use it through the Internet. This is actually more of a response to this question, but I thought would still be relevant here. Click on Send CTRL+ALT+DEL (or use the Shift+Ctrl+Del keyboard shortcut). Remoter desktop doesn't support what you are wanting.

Teamviewer ctrl alt del