Response.Redirect after Response.Flush

[GlenW]

Is there a way I can call Response.Redirect after I've done a
Response.Flush?
I send some html to load an animated gif that plays whilst my page loads,
it has some extensive database calls to process. However, when I try to
redirect to my error handling page, if there is an error, I get a 'Cannot
redirect after HTTP headers have been sent' error.
I've got round the problem by using a javascript function in the body
onload event that checks a hidden field whose value is set when an error
occurs, but this does not seem very elegant.
Any ideas?