System.Windows.Markup.XamlParseException when running winfx june ctp application on winxp sp2 machines

I have been receiving a "System.Windows.Markup.XamlParseException" on several different computers when running a wpf application we have been building as well as when trying to run the code from www.valil.com/winfx site. We have installed the WINFX beta 2 release on 4 computers running winxp, and they get this issue. However, two others with vista beta 2 and three computers running winfx with all the developement tools do not seem to have this problem. We really need some advice on how to solve this issue, and any advice would be appreciated.

Steve

Visual Studio 200822

The most likely cause is that the machine has mismatched dlls.

I thought of that possibility, but I am unsure where to start looking. All four machines that failed had winfx installed the first time with beta 2 that came out several back. Any suggestions

Steve