C#.NET - Problems with stream read/write timing glitches

I'm trying to read from a Stream and write to another Stream. The output stream is a disk file, whereas the input stream is one provided by SharpZip (http://www.icsharpcode.net/OpenSource/SharpZipLib/Default.aspx).

I've put a BinaryReader on the SharpZip Stream and a BinaryWriter on the disk file's handle.

Whenever the stream data is copied I run into glitches that result in truncated files, 0-byte files, files that are closed before they've started to be written, etc. In general it appears that BinaryWriter is executing in a different, slower thread than the read operations. However, I haven't put any multithreading code into my app.

Here is applicable code:
                      Outfile = new FileStream((UT2004Location + en.Value.ToString()), ((bOverwrite) ? (FileMode.Create) : (FileMode.CreateNew)), FileAccess.Write);
                      Output = new BinaryWriter(Outfile);
                      // Read in data
                      Instream = Infile.GetInputStream(Infile.GetEntry(en.Key.ToString()));
                      Input = new BinaryReader(Instream);
                      Size = 2048;
                      while (true)
                      {
                          Size = Input.Read(Buffer, 0, Buffer.Length);
                          if (Size > 0)
                          {
                              Output.Write(Buffer);
                          }
                          else
                          {
                              break;
                          }
                      }
                    Input.Close();
                    Instream.Close();
                    Output.Close();
                    Outfile.Close();

Thanks in advance,

mtyrce