I had looked at a problem with IE where the user worked frequently with data input into form fields. The problem that they had was that it would not start giving the auto complete suggestions as they started typing.
I checked Internet Options -> Content -> AutoComplete Settings and verified that the "Forms" option was checked. Since it appeared that everything was enabled to do what the user wanted, I selected the "Delete AutoComplete history" option. After clearing the history, the auto complete started working again.
I am unsure whether or not the files containing the information for this feature were corrupt or possibly too large to continue working.