Opening files within SharePoint 2010 do not open correctly. Fix this by changing the 'Browser File Handling' from 'Strict' to 'Permissive' using Powershell

Create a PS1 file with the code below (Change the $url value to the URL of your web app)

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$url = "http://webappname"
Get-SPWebApplication $url | ForEach-Object {$_.BrowserFileHandling = “permissive”; $_.update()}
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This will update the web application Browser File Handling from 'Strict' to 'Permissive'