In Word I am unable to type the same key more than once. Ideas?

[dressagerider]

When typing I inadvertently hit some key. A message came up( uncertain as to
the message) and I thought I just Xed it out. NO. Now I am unable to type a
single character more than once. (i.e. can't type puddle - will not allow two
"d"'s in a row. Any suggestions?

 

[Greg Maxey]

Is it "won't" type two characters in a row, or won't without a delay? If
the later, go to Control Panel>Accessility Options and turn off "filter"
keys.