I have seen a similar issue before. It was workflow related for me. Here is how I fixed it:
In SharePoint Designer, open the site where your forms library resides.
File
Inside of Workflow Designer, go through your typical steps (i.e. give it a name, etc). Be sure to check "Automatically start this workflow when a new item is created."
Inside of the Workflow Designer, under actions, select "Send an Email." This of course, will add the action "Email this message."
Click this message in the email this message box.
In the Define email box, fill in your subject, to, from, fields (usually I just have this pull AD account info, from columns CreatedBy, DirectSupervisor, depending on the type of process).
On your SharePoint page, go to the form library where you InfoPath form is stored, and ensuring it opens in-browser, click on an existing InfoPath form and copy the URL.
Copy the URL. Such as this: http://ServerName/SiteName/_layouts/FormServer.aspx?XmlLocation=/SiteName/LibraryName/Form1.xml&Source=http%3A%2F%2FServerName%2FSiteName%2FLibraryName%2FForms%2FAllItems%2Easpx&DefaultItemOpen=1
Insert the link as a hyperlink into your email dialogue box within SharePoint Designer.
Highlight the part of the URL that comes after the XmlLocation parameter: /SiteName/LibraryName/Form1.xml
Click the add lookup to body.
The Window, "define workflow lookup" dialogue box should appear. Select Server Relative URL from the Field drop-down list box, and click okay. The link should now look like the following:
http://ServerName/SiteName/_layouts/FormServer.aspx?XmlLocation=[%LibraryName:Server Relative URL%]&Source=http%3A%2F%2FServerName%2FSiteName%2FLibraryName%2FForms%2FAllItems%2Easpx&DefaultItemOpen=1
In the Define Email Workflow box click okay. In SharePoint Designer publish the workflow to the Forms library. Now when a user submits a form, it should include a direct link to the form...