In rare cases the installation procedure fails to register a required component of AccuRender 4. This can be solved by downloading, unzipping and double-clicking on this file.

Register_AccuRender_Libraries.zip

After running the batch file, you should get the message:

"DllRegisterServer in c:\program files\common files\McNeel Shared\AccuRender Libraries\ar4_nse3.dll succeeded."

Then restart AutoCAD.