Installing Office XP - Invalid Product Key

[Sharon]

When I try to install Office XP I keep getting the error
message that I have not entered a valid product key.

I've double and triple checked the value. I also tried
entering it in both lower case and upper case.

I have the original materials with the yellow product key
sticker on the back of the CD jewel-case. This copy was
purchased from a highly reputable source so I'm certain
it's not bootleg.