My roommate just had this problem with Microsoft Word 2003, and I found the fix using the Google search engine. Here’s what you do:
Tools -> Options -> Edit
Check “Typing Replaces Selection”
That’s all my roommate had to do. For the sake of completeness, the fix also says:
Tools -> Options -> General
Uncheck both options that have WordPerfect in them
Hope this helps someone.

Thanx alot.
After i had worked on my manager’s Laptop,
its backspace stopped working.
he kept saying that i did something to his laptop.
I did what you suggest and its working now.
By the way, i had this problem with my pc too, and now its working.
thanks
Thanx alot.
After i had worked on my manager’s Laptop, its backspace stopped working. he kept saying that i did something to his laptop.
I did what you suggest and its working now.
By the way, i had this problem with my pc, and now its working too.
thanks
You are my hero! Thank you for posting this fix. Saved me from buying a new keyboard!
huge appreciation, was irritating the pants off me. you’re the daddy.
thank you who ever you are, my comp used to work and then just stopped one day and that has been bothering me forever, I knew there had to be a fix… thanks so much