500 HTTP error on "Manage Display" tab after changing layout with Display Suite! What should I do? I changed the layout to "One column" with Display Suite on a given content type's "Manage display" tab, which has many (~30) fields. I'm also using Field group module with multiple groups.
After saving, DS has set some group's parent elements to "Disabled". OK, I changed it, I dragged these to the enabled part, and after saving, I got a 500 HTTP-code when going to "Manage display" tab after a long waiting time!  

What should I do? Can I simply uninstall Display Suite module? Will it reset the display to my original settings and field orders? 

Thank you for any kind of ideas!



EDIT

Uninstalling the module did NOT solve the problem.... I'm in a real big trouble, because I don't know how to reset the display... 
Any ideas?
Had the same issue, deleting the rows corresponding to my problamtic content type from the table "field_group" solved it. This way I didn't lose my entire field group settings.