In the world of InfoPath, you may have noticed the the url for an open form is crazy big! I ran into a problem in the past when I ran out of space in the url. Sometimes this happens if the form is nested a couple of levels down in a site. Whenever you open a new form in the browser, your url will look like the following:
You can shorten the above by removing all of the items in bold. It will look like this once you have finished:
As a best practice, I do this each time I have to setup a link to an InfoPath form. This way, I keep my urls short and will not have any issues of running out of url space.