Applescript freezes with Safari

Question

When I ask Applescript to wait until a web page in Safari has fully loaded, it seems like Safari often simply refuses to answer and my applescript consequently freezes. Is there a way around this? Here's a simplified version of what I'm asking Safari to do. I added the timeout so you don't have to wait 2 minutes for the script to time out:
with timeout of 20 seconds
          tell application "Safari"
  activate
                    repeat 100 times
                              set the URL of document 1 to "https://accounts.craigslist.org/login"
                              repeat until the text of document 1 contains "Account Log In"
                                        delay 1
                              end repeat
                              set the URL of document 1 to "http://humanpotentialcenter.org"
                              repeat until the text of document 1 contains "Want to know more?"
                                        delay 1
                              end repeat
                    end repeat
          end tell
end timeout
It doesn't have any problems when I run it on my 10.5.8 system, but it does freeze the Applescript when I run it on my 10.8.5 system. Suggestions?

Answer 1

The web sites visited are pretty much the same on either the iMac or MacBook. These are well known sites for the most part. I always keep updates current with any of the software I use including Adobe...