If a form has multiple <input type=file> elements and files are not assigned to all of them, clicking the submit button will cause the program to hang.
This fails in Safari 4.0.3 and the current WebKit nightly (46919). This is not a problem in Safari 3.2 (4525). Unfortunately, I don't have other builds to test with.
This works properly in Safari 4.0.2.
Created attachment 34789 [details]
I cannot reproduce this. Do you have an example page where this happens? Do you have any "Safari enhancers" installed?
Please attach a sample made with Activity Monitor utility while Safari is hung (double-click Safari in Activity Monitor process list, then click Sample button).
Created attachment 34792 [details]
Fixed some mistakes in original test, but still cannot reproduce.
Created attachment 34793 [details]
HTML test case
This page demonstrates the problem. Select a file at only one of the file selectors (say, Certificate), and leave the other empty. Hit the "save" button.
Created attachment 34794 [details]
Sample from WebKit after hitting submit
from Webkit r47189
Does the test case fail for you? Do you need any more information?