The code below works fine, the problem is the 1st two lines are appearing on screen. It basically loads the PDF but I can't see the btnAcceptProposal change name or become enabled. Tried a Thread for the load but it broke. Anyone got any ideas - it's a web application protected void btnPDFProposal_Click(object sender, EventArgs e) { btnAcceptProposal.Enabled = true; btnAcceptProposal.Text = "sss"; byte[] p = Order.Proposal; Response.AppendHeader("content-disposition", "attachment; filename=Proposal.pdf"); Response.ContentType = "Application/pdf"; Response.Clear(); Response.BinaryWrite(p); Response.End(); }