There are a few things to look at for this.   The  most common ones are: Internet security and/or cookies need to be cleared.

#1 clearing your cookies/and internet files help

To clear cookies/internet files"
In your browser (if it is Internet explore) Go to “Tool”  then “internet options” click on the “general” Tab then Click on ”Delete cookies” and  “Delete files”  also make sure to check the “Delete all off line files” box

Google Chrome:

Go to the wrench icon on the far right.

Now "Tools" then "Clear Browsing data"

Make sure " Delete cookies and other site and plug-in data"

Click "Clear Browsing data"

#2 - Internet security is set to “high”.  To change this go to your Internet explore or what ever browser you use and go to “Tools” then down to “Internet Options” after that opens click on the “Security tab” then click on “default level”  here move the slide bar next to the levels to medium or lower make sure and to “Apply” changes