When you download any file with Google Chrome and click on a little arrow down, one of the options is "Always open files of this type". If you select this option, all files of that type will be automatically opened immediately after downloading.

It may not be immediately obvious how to reverse this option and stop files opening automatically after downloading.

If you clicked on this option accidently you immediately untick the same checkbox in the download bar. But if the download bar timed-out and hid or you restarted Google Chrome, the download bar will no longer appear after downloading files of the type in question. 

To reset auto-opening settings and stop all files from opening automatically after downloading, perform following:

Go to Google Chrome > Settings > Show Advanced Settings, and in Downloads section click Clear Auto-Opening Settings.

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10.2014