StaffHi Anupa,
It looks like something is generally wrong with your environment. The following script works perfectly for me (BTW, the script just inserts the command and does not make it be executed as it happens in your case):
Sys.Process("cmd").Window("ConsoleWindowClass", "C:\WINDOWS\system32\cmd.exe", 1).Keys("~ ep")
BTW, the Excel issue you mentioned earlier can be possibly caused by your add-in. I recommend that you check whether the strange behavior can be reproduced: 1) without TestComplete; 2) on another machine.
As a workaround, try using the script mentioned earlier (the one provided in the Testing Console Applications help topic) - it works with the standard input/output streams of the console window directly.
