Links in InfoPath Email not always working

Question

I am creating a few infopath forms where all of the rules are inside the form sending emails along an approval chain (not using any workflows in SharePoint Designer). I have email views sent as emails at certain stages of the process to specific people. The links I have inserted inside the emails to point back to where the form is stored in the SharePoint Library does not work all the time for users. When they click the link, they sometimes get a permission error even though they have access to the library. Other times, the link works perfectly. Anyone have any ideas of why this is occuring? I am using SharePoint and InfoPath 2010.