It was always an issue for me as having multiple CPU but single monitor and I hate most when I have to access a System remotely because there is no option for CTRL + ALT + DEL, one of any computer users most favorite key combination. : )
Finally I found it, here is a solution to access CTRL + ALT + DEL over remote desktop, just need to replace DEL with END. So combination while using remote desktop is CTRL + ALT + END
Cheers!!
