title: I do not have a 'Any CPU' option present in my Configuration Manager
body: <p>I have read several posts about the configuration manager in VS2010 (or before) but I can not find my problem.</p>
  
  <p>I have a solution containing 6 projects. 
  When I open the Configuration manager, I can select:
  'Active Solution Configuration' with values Debug, Release, New or Edit.
  Áctive Solution Platform' with values Any CPU, Mixed platforms, x64, x86, New or Edit.
  And for any of my 6 projects the configuration (Debug, Release, New, Edit), 
   Platform (non startup projects: Any CPU, New, Edit and startup project: x64, New, Edit).</p>
  
  <p>For all projects except the startup project the only (real) choice for Platform is 'Any CPU', which I think is fine.</p>
  
  <p>However, for the startup project I only can select x64 so I assume running it on 32 bit Windows OS's will be a problem?</p>
  
  <p>I have played in history a bit with the values and now somebody mailed me this error he gets:</p>
  
  <blockquote>
    <p>the version of this file is not compatible with the version of Windows
    you're running. Check your computers system information to see whether
    you need an x86(32-bit) or x64 ( 64bit ) version of the program, and
    then contact the software publisher</p>
  </blockquote>
  
  <p>(also when I select the x86 platform I only can select x64 as platform in my startup project, while others are set to 'Any CPU'.</p>
  
  <p>When trying to add Any CPU to the startup project, I can select it but it asks to copy the settings and I only can select x64 or empty. Selecting either of them results in the error:</p>
  
  <blockquote>
    <p>This platform could not be created because a solution platform of the
    same name  already exists.</p>
  </blockquote>
  
  <p>I assume it was previously set to x86 but I'm not sure, anyhow, how can I get the 'Any CPU' selection back for my startup project?</p>
  
  <p>UPDATE: SUDDENLY I COULD ADD THE OPTION 'ANY CPU' WITHOUT GETTING AN ERROR.
  So my problem is solved ... </p>
  
  <p>I only don't know why it didn't work the first time ... I just closed the window and started it again and it was possible.</p>