Deleting File Through C# Program.

Hi,
In my application i am taking multiple image files from user using openfiledialog and display those image files in flowlayoutpanel. After pressing on Insert button i used to copy all those images in a folder (C:\Images). When there is no file exists the file get copied easily, but if it exists i delete the file, but while deleting file it shows error
"The process cannot access the file"C:\Images\xyz.jpg" because it is being used by another process"
 
The code i used is
if (File.Exists(destFileName))
{
File.Delete(destFileName);
File.Copy(sourceFileName, destFileName);
}
else
File.Copy(sourceFileName, destFileName);


Is it because i display the images in flowlayoutpanel while deleting. But before execting above code i clears all controls added in the flowlayoutpanel. Still the error occurs.. What should i do?
Regards,
Vidya