If you want the 64 bits version to be launched, apply the following actions :
How to change Photoshop 32 bits by Photoshop 64 bits
- Open the windows registery by using the "regedit" program (open a shell window and type regedit).
- If the following branch doesn't exist in your registery, create it : [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Adobe\Photoshop\12.0]
- Inside the "12.0" branch, create a string value named "ApplicationPath" and give it as value the path of Photsoshop 64 bits (C:\Program Files\Adobe\Adobe Photoshop CS5.1 (64 Bit)\). You can do this by right clicking on "12.0" section and then choose New -> String Value
- Inside the "12.0" branch, create a string value named "PluginPath" and give it as value the path of Photsoshop 64 bits plugin folder (C:\Program Files\Adobe\Adobe Photoshop CS5.1 (64 Bit)\Plug-Ins\).
- Close regedit. That's all.