This issue should be pretty rare, and is really only for Internet Explorer and/or iPhone/iPad users using Safari, however, here are the steps to alleviate the problem.
Part 1 is for Internet Explorer and Part 2 is for the iPhone/iPad.
PART 1: Internet Explorer
From the browser window, go to "Safety" and click on it. Then click on "Delete Browsing History."
A window will appear and you'll want to make sure "Temporary Internet Files" and "Cookies" have a check next to them. Then click the Delete button.
PART 2: iPhone and/or iPad
If you are using an iPhone or iPad with Safari, you may have run into a similar problem. Here is how to fix it.
If you are using iOS 7:
Tap on the Settings button. Then scroll down to Safari. Then change the Block Cookies option to Never as shown below.
If you are using iOS 6:
Tap on the Settings icon and then tap on Safari and then tap "Accept Cookies." On the next screen set it to "Always."