Arrrgh.

I'm dealing with a poorly written web application--Basically a big and moderately complex form to fill out. However it has unique features that make it extraordinarily difficult to use

1. If you hit the backspace or Enter key, and your cursor is not in a text field you will lose all your work.
   
2. Most fields will initially allow any value-however the form will not allow you to save if the values are not acceptable. It won't complain about them until you try to save, then it will inform you that you cannot save until you correct a single error--If you have two errors, it will only tell about one at a time, giving that many more chances to hit backspace at the wrong time
3. Soeme date fields are directly editable, others require you to click on a calendar. The ones requiring the calendar will let you put the cursor in their field, but if you backspace, will delete all your work.
4. You can make a copy of an existing similar form rather than starting fresh. Not everything will be copied--Many of the fields that would be useful to have a copy of are not, and many of the fields that will always need to be edited or changed are copied.

There are other peculiarities, but these are the most bothersome. I'm constantly amazed at the lack of usability that is considered acceptable in software.