I acepted a sugestion in Word to use a keyboard program to reduce errors. Now
I can't undo the change, and I can't type double letters (e.g., tt in letter)
or backspace under certain conditions.
I think that the keyboard program you're referring to is the autocorrect
feature in word. If you type 'teh', it will autocorrect it to 'the'. If
that's the case, you can remove any entry that is causing problems (e.g.
letter -> leter) in the AutoCorrect Options dialog. This is in Tools/Options
in 2003 (I think), or File/Word Options/Proofing/Autocorrect options in 2007.
If that's not the problem, then explain a little more what you typed and
what happened letter by letter. Also, if you know if the Keyboard Program is
part of Word, or if it is a non-Microsoft program, that would be helpful too.