Application loads Acrobat 9.1 for PDF's instead of Reader x.x

We have an enterprise application that has PDF's embedded in its data collection. Pretty straightforward, loading a PDF from the application runs Windows ShellExecuteEx function (http://msdn.microsoft.com/en-us/library/bb762154(VS.85).aspx) and sends the verb open.

When we have just Reader 9.1 (or 8.0 or 7.1) it loads just fine with Reader. We lay down Acrobat 9.0 (or 9.1 with all the latest) along with the setting to always open PDF's with viewer, this application always loads the PDF with Acrobat 9.1.

Digging further into the file association, I select PDF and go to Advanced. I select the verb open and there it is, reference to Acrobat 9.x instead of Reader. I change it to the path to Reader, press OK. I go back, it changed it back.

Opening direct PDF's from web pages or opening PDF's all load properly in Reader, but this rather intrusive and forceful way that Acrobat 9.x does not allow to change the open verb type for the file association is obviously preventing me from fixing this issue.

Any suggestions?
Thx