unwanted hidden field and missing for attribut in checkbox (Typo3, Powermail)

I have a problem with Typo3/Powermail. I tried to add custom checkbox images and ran into problems with IE.

I found another website based on Typo3 with customized checkboxes working fine on IE too.

What is weird is, that my html form structure (generated by Typo3/Powermail) looks different.

Here is my checkbox html:

As you can see, I have a field with type hidden inserted, don't know why. And my label has no "for" attribut.

This form field here (Typo3/Powermail as well) looks nice:

Here we have no strange hidden input field, and there is a "for" attribut in the label.

Can someone help?