VS 2010 - Image File Much Smaller After MetaData Edit

I'm editing jpg metadata and when I'm finished the file is less than half the size but ok, IE I can see modified tags correctly via windows explorer. But if I edit the same file again its down to 16k and corrupted. The image being edited is the standard desert.jpg found in the picturessample pictures directory.

I'm using the following
Public Sub Put_FileMetadata(ByRef glb_UserArray() As String, ByRef glb_SecurityArray() As String, ByRef glb_InputParms() As String, ByRef glb_InError As Boolean, ByRef glb_ErrorNumArray() As Long, ByRef glb_ErrorDescArray() As String)
On Error GoTo error_handler
' Initialise Variables
[Code] .....