>>>I tried
>>>
>>>

this.EnableViewState = false;

>>>
>>>in both the control and in the form the control gets loaded to. Same error occurs.
>>>
>>>
>>Are you using AJAX?
>
>I have a ScriptManager and UpdatePanel on the page. Inside the UpdatePanel is a table. I'm addining my control to the table

Try going with Viv's suggestion. That problem is very tough. Good luck in solving!