I am asking the same question as this:
http://stackoverflow.com/questions/691323/trying-to-upload-a-non-existent-file-in-internet-explorer-form-is-not-submitted

I'm not sure if the topic starter found a solution,
since he did not post the answer.
So, I'd like to ask you guys this question again.

I have type=input in my form, and a submit button.
If I type garbage input into the textbox (like the text "abc") in the file control's textbox,
and click the submit button, the form is not submitted to the server.
AND, no feedback is given to the user.

Instead of this "Is-the-submit-button-broken?" behavior,
is there a way I could notify the user that the file does not exist?
(I am aware this is not possible, except with ActiveX, but I don't want to go into that)

My client wants to hide the textbox of the file control,
but I'm not sure if this is a good design.

What do you guys suggest?

(If it makes any difference, I am also using this jquery plugin: http://www.fyneworks.com/jquery/multiple-file-upload/)