Cannot view PDFs on Internet Explorer 9

Hi,
I have just installed IE9 but i am unable to open PDF files in the browser. I have tried Adobe reader 10 and Adobe 9, but both have refused.
Before I installed IE9 i didn't have this problem.
I get this error:

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.
Need a solution, thanks.
