Form fields lose data if error in input

Hi,

I am new to Drupal and impressed with what I've seen, so I hope I'm not making a fool of myself here :-)

There is a usability issue that if one field in a form is invalid, the data of the majority of the others is forgotten when the page with the error message is displayed. If that didn't make sense:

1. Go to the edit my profile page
2. Enter a new password into one of the password boxes
3. Add content to some of the textareas/text inputs
4. Submit the form
5. Notice how much lis left

Is this a known problem? Forms that do this are very annoying; while the back button can be used to get back to the data, it kind of defeats the object of the error message being displayed on the same page as the form.