Now when I create a new AspectJ project, I immediately get a red exclamation mark next to the project entry, along with the error message "The container 'AspectJ Runtime Library' references non existing library 'file:\C:\Program Files\Eclipse\eclipse-sdk-3.7\plugins\org.aspectj.runtime_1.7.0.20120703164200.jar!\aspectjrt.jar'".
Checking the file system, the Jar file is there, and it contains a top-level "aspectjrt.jar". So the error message is misguiding!
This looks like a regression. Last time I ran into this, I was told to switch to the "dev" update site, which solved the problem then.
Now I'm unable to have a working AspectJ project in Eclipse. I wonder how other people do it ...