Hello,
Can you please try clearing the clipboard using 'Clear Clipboard' command before sending 'Ctrl+c' keystrokes? You can find Clipboard command under 'Miscellaneous' command category.
If it does not help, please upload the screenshot of error that you receive. In addition, is it possible for you to upload your task as well so that we can look into it? You can locate your task by selecting your task from Task List, right clicking that particular task and selecting 'Locate on disk' from context menu.
You can also email the screenshot and task at
http://www.tethyssolutions.com/support_form.htm