After doing a bit of searching on Google, I came upon this post “Windows key “stuck” in Remote Desktop…“. This seemed to accurately describe my problem. But, the first comment in the post was able to work around my particular problem:

The best workaround that always works for me is:

1. Close the RD window
2. Open new RD but make sure the “Apply Windows key Combinations” is set to “On the remote computer”
3. Now press the Ctrl+Alt+End and lock the computer
4. Log in again and it should work.

amirhp
/’L'\mir

I put this here so that I can remember it for the next time. (Yeah, I pretty much expect that this condition will happen again.)