Thanks for the report. We didn't change anything in Ctrl + Alt + Del mechanism in this version.
Am I right assuming that rebooting of the remote PC helped? Sometimes it's actually necessary to reboot the remote PC after Host installation. Especially when it comes to using "system" features like Ctrl + Alt + Del.
I've just made a quick search in our license database and found that you have a 5-PC commercial license.
So my remark above about 22 PCs is incorrect. With your license key (for 5 PCs) you can control 5 computers. If you have other commercial keys I didn't find just let me know via email email@example.com
1. You didn't accidentally pressed the Full Control / View toggle icon (it's the first icon on the toolbar in the Full Control mode). When it is pressed, you are in Full Control mode. When it isn't, you are in View only mode with mouse and keyboard not working.
2. Provided that #1 is not the case, does this happen all the time or do the keys work after you re-initiate the remote session?