can't open decrypted file but Explorer preview shows contents

I’m using Windows 7 Home Premium and a trial of CIS Pro 2013. There’s an encrypted file in my Shared Space which I decrypted in the Sandbox. I can see the decrypted file’s contents in Windows Explorer’s preview but I get an error (see image) when I try to open it. Can someone please explain this?

Edit: I probably should have mentioned that the decrypted file is not in the Shared Space but is in a folder that I have ownership of.

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