Hi,
My guess would be that your DFM file has a property that doesn't exist for your version of AC Controls. Normally if you open the form in the IDE it will prompt you about this and remove them for you. What you may need to do in your case though is to look at the form DFM (view the form, press ALT-F12 to show the form code) then search for a line that mentions ThirdScrollControl and delete that, then recompile your program and run it again. If you can't find that text in that form then look in other forms that you may be opening, I'm sure you'll find it in there somewhere (use a text editor to view the .dfm files if you don't know a better method). Good luck!
Regards,
Hamilton