Q. I am trying to get access to Lehigh google groups after getting an invitation. I am not allowed to access it. What's wrong?

In order to use any of the Google Apps services, you need to first  log into Google Apps and agree to the terms of service. Go to g.lehigh.edu, picking any of the apps, and agree to the terms of service.  Once you have done this and successfully logged in, you will be able to respond to invitations to Groups and other email regarding Google Apps.