The process cannot access the file 'c:\temp\my.pdf' because it is being used by another process.

I've developed a popup email .aspx used on our intranet based web app that is auto generated with .pdf's attached. I'm developing with VS 2008 ASP.Net 3.5 C# and System.Net.Mail.MailMessage. I can create and send the email with no issues. The problem is with any attempt to open or delete the attachments I get the above error. The .pdf's a copied with the following code:
                FileStream fsr = new FileStream(inFilename, FileMode.Open, FileAccess.Read, FileShare.Read);
                BinaryReader reader = new BinaryReader(fsr);
                byte[] bytes = new byte[fsr.Length];
                reader.Read(byte ...