Quick “I-hate-InfoPath” tip: I had a bunch of dropdowns with Swedish text in them as values. InfoPath then proceeds to flag this text as faulty. “Ok” I think, “Let’s just switch that spellchecker off”. No dice. There is no setting for the spellchecker on dropdown menus. Once it’s there, it won’t go away. Not very user friendly.
The solution to this, I found, is to change the dropdown to a textbox via the “Change this control…” action. And then switch off the spellchecker. You can then switch the control back to a dropdown and the spellchecker is removed.
WARNING: This will reset all connections/preset values on the control, so be prepared for this.