Cannot Find Server After Form Submit

I'm attempting to submit a multipart data form that updates an access database and uploads an images via aspSmartUpload. The form used to work, but no longer does.When the form is submitted, the target asp page returns as "Page Cannot Be Displayed". It's not a 500 error, it's like a 404 error.

Refreshing the page will bring up the target page (with obvious asp errors). I have replaced the asp target with a simple html page that produces the same results. I know it's a little vague, but it's all I have to go on.