owner must be set before initialize on tabcontrols

hi,

I have a ajax tabcontrol running on my asp.net page and onload i am getting this error message:

"sys.InvalidOperationException: owner must be set before initialize"

I dont get this error message all the time but sometimes.  but when i get this error and if i refresh the page then the page loads fine.
I am getting this error message on dotnetnuke module

How do i fix this?

Thanks