Browser 開啟PDF時出現以下錯誤訊息怎辦? "The Adobe Acrobat/Reader that is running cannot be used to view PDF files in a web browser......"

明明Adobe Reader 版本已經是XI (11)，而在Adobe Reader 內的瀏覽器選項也已經正確選擇，但在瀏覽器開啟PDF時出現以下錯誤訊息怎辦?

"The Adobe Acrobat/Reader that is running cannot be used to view PDF files in a web browser. Adobe Acrobat/Reader version 8 or 9 is required. Please exit and try again."

我當時的情況是該電腦同時安裝了Acrobat9 和Adobe Reader11。只要把兩隻軟件都移除，再依序安裝Acrobat9 和Adobe Reader11便解決題。