This is just a bit of a quick and random (but useful) tip.
You probably already know that to send CTRL + ALT + DEL to a machine that you’re RDP’d to, you use the CTRL + ALT + END combination instead; but what if you’re trying to send the CTRL + ALT + DEL to an RDP session inside another RDP session? The first machine you’re connected to gets the key combination, not the machine inside the machine you’re connected to.
The answer? The On-Screen Keyboard. It’s under Programs -> Accessories -> Accessibility, and allows you to send key combination from the machine that is connected to the machine you want to send your key combination to.
I found this particularly useful when trying to bring up the task manager of a machine that I couldn’t risk re-connecting to, as it was unstable and would probably have kicked me off altogether.