If you're seeing this error with the demos, too, check a couple of things:
- Make sure first and foremost that the DLL is infact in the BIN directory of the Live Demos project. It's possible that you have tried to copy it in the past and inadvertantly moved it.
- Also make sure permissions are not an issue. I'd usually expect a different error if this were a security problem, but it never hurts to check. Make sure the account running the demos has full access to the project location.
If you still have trouble, I'd suggest starting with a clean slate to make sure you're environment is in good condition. By that I mean: uninstall the RadControls, download the latest release trial (2008.2.1001), re-install the RadControl, and then try browsing the demos. You also need to ensure you've got .NET 3.5 installed on your system to browse the .NET 3.5 demos.
Hopefully this will help you get further. If you get very stuck, make a small demo project with the problem and submit it in a support ticket. That will enable us to provide targeted help to your situation.