Ive tried replicating your problem with multiple groupbox's in a tabcontrol with 3 tabs. I have no errors occur tho..
although i have used wpf before and havn't encountered ur problem im curious as to why u switched ur project over to wpf from what i can gather all wpf does is speedup graphics drawing, what am i missing
Yes please Eye candy in my experience.. Source: http://mdavey.wordpress.com/2007/09/05/wpf-vs-windows-forms/