I have a frequently occurring problem where I cannot end the execution of Rhino commands. For instance, if I want to draw a poly line, Rhino will not accept enter from the keyboard or by right clicking the command line and choosing enter form the pop up menu. Rhino neither deletes objects if I press del or type del. Deleting works through the Edit menu. While stuck in a command it is possible to start a new command by clicking on icons or menu items. It seems that there is some sort of a problem with keyboard input.
I get this problem several times a day, which forces me to restart Rhino. Has anyone else been suffering from this?
I am running Rhino 5, 64 bit on Windows 8. (5.1.30129.1756) 01/29/2013
I don't know if I've had that exact thing happen of enter not working (does the spacebar work?) but I've certainly had things like that happen and the culprit has been that with all the CTRL and SHIFT+clicking I've accidentally enabled some Windows keyboard "accessbility" or even language change option. If it fixes itself when you restart Rhino, though, I'm not sure if it could be that.
This is also a frequently reported issue on the Grasshopper board - are you running Grasshopper?