Form checkboxes grey instead of white?

[pat_nospam]

When I start a new record, most of my forms that have checkboxes will suddenly turn white, waiting for a "check". But I do have one misbehaving form that 75% of the boxes will turn white/empty, while 25% remain sort of grayed out..

Any ideas?

 

[pat_nospam]

For example, this is a screenshot of the boxes after checking one of them, half are grey, half are white.