file upload issues

hi,

i had a friend test my form

one of the things he did was try (on purpose) to upload a file bigger than image-size limit
he reported -
"...i put in a picture for upload that did not fit the criteria
got the message that it was not right, but i could not remove  the info i put in -
tried clicking the mouse to delete and the delete button on the keyboard 
- couldn't get it out -

it wouldn't let me proceed beyond there
(using firefox)..."

is this a bug, or user error?

thanks,
ken