The Operation could not be completed. Invalid FORMATETC structure

I encountered this error once while working on a ASP.NET web application and trying to place Ajax AutoCompleteExtender on one of the form's textbox in design mode (vs 2008).

I did this quick hack and it worked, see if its the same for you:

• Remove the Tab and controls from toolbox in visual studio.
• Add a new tab for holding Ajax toolkit controls
• Load toolkit controls by browing the ajaxcontroltoolit.dll (make sure you select the version you want to load) and fill the required tab with controls
• Now when you will drag and drop the controls on aspx form, it will not show up previous error

Don't forget to post comments here if it worked for you!