If you're a medical student using UWorld to study for USMLE Step 1, you've likely been admonished with this message (many times) more than once while a test is running. Well, this is the 21st century, and we have better things to do on our computer besides sitting through an entire 40-question block, like checking Facebook and tagging ourselves on Twitter, amirite? #medstudentlife #studyhard #futuremd /s
In any case, it's not like disabling the clipboard and copy/paste does anything to deter people from capturing UWorld content through alternative means such as screenshotting or using their phone's camera.
However, if you value multitasking and the ability to use the clipboard and copy/paste unmolested while UWorld is running, the solution is to run UWorld in a virtual machine. There are several free virtual machine solutions across all major platforms - VMware Player, VirtualBox, etc. On Windows, my vote goes to VMware. Just make sure to disable clipboard sharing. In VMware, for example, make sure "Enable copy and paste" is unchecked in the VM Options / Guest Isolation section:
In VirtualBox, the same option is aptly named "Clipboard Sharing" and you can set it to either Host-to-Guest mode or disable it entirely.
With the guest OS's clipboard isolated, you won't have to worry about UWorld hijacking your clipboard ever again. In addition, since UWorld is blissfully ignorant to the world outside the guest OS, you'll be able to take screenshots to your heart's content.
Happy studying, and good luck on Step 1!