So, I have a very intermittent issue with a Form Library on SharePoint 2013. At random, a user will go to a page with a form library web part. They click "+ new document" and they get a prompt to upload a document (they should get the form displayed in the browser). If they click the web part heading and go into the library, and then click "+ new document", the form opens up in the browser like its supposed to. Also, the error does not appear if this user accesses the form with Firefox or Chrome...only Internet Explorer.
Now, while this error is occurring for a user, I can have ten other users who do not get the error and can open the form like normal.
Any ideas what could be causing this behavior? The form and the library are definitely configured properly to open in the browser. I've tried re-publishing the form to the library, having the user in questions flush their cache, etc.