I discovered that the Magic SysRq key Ctrl + Alt + PrtScr + r frees the keyboard after such errors. I don't know if it's a "good" way in technical terms, though. :)
Contributions to the project are always appreciated, so if you would like to support us with a donation you can do so here.
Hosting provided by Mythic-Beasts. See the Hosting Information page for more information.