Thanks, Ken. Here is the version I am using.
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2) Gecko/20070219 Firefox/2.0.0.2 Web-Sniffer/1.0.24
I was able to get this to work on a different machine using this exact version of Firefox listed above. The difference between the 2 machines is that the one that froze the browser had the latest version of Adobe Acrobat Professional (8.0) and the latest version Adobe Acrobat Reader (8.0). The machine that worked contained verison 7.05 of Professional and 6.0 of Reader.
Is it possible that the problem has to do with the plugins associated with the latest version of Reader and/or Professional?
-Tom