can't execute some exe files in win7 32bit virtualbox VM share folder which is created by ubuntu 64bit host

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http://askubuntu.com – I installed ubuntu12.10 arm64 version, then installed virtualbox 64bit and win7 32bit VM. I created /mnt/share folder and shared it with win7. In win7 share folder, some exe files could be executed, but the others couldn't. The error says, the path doesn't exist. But if I copied those files into win7's own folder, it could be executed. I'm confused. Could anyone help me? Thanks, Lisa (HowTos)