I'm going to answer my own question because I just realized what it is. I'm clicking on a folder within my documents which contains about 3 gig. It must be doing a full scan on this folder. If I create a folder at the C: root I can access the security tab in a second.
I have a laptop and a desktop, both running Windows 7 Home Premium and noticed that on the desktop, if I click on any folder --> properties --> Sharing it stops responding. I have to wait about 5 minutes to access the sharing options. Has anyone noticed this?   Thanks. Jeff    
Windows explorer not responding when clicking sharing tab