Why a xml file remain being used by a process after loaded with MyDoc.Load method ??

Hi

I have a VB NET application.

In the main form, I am creating an xml file, and after that, I am calling a child form that tries to read it xml file, and proccess it.

The first time that I run it process, all is OK, in other words, the xml file is successfully created, after that, the other form is called, and them, the xml file is successfully acceded.
.
The next times, the xml file is created ok with new data, but when I call the child form, I can not open the xml file, and I receive the following error:

The process cannot access the file 'C:\Documents and Settings\LUIS\Local Settings\MyCompany\Cache\MyFile.xml' because it is being used by another process.

The only way I can release it, is to exit of my application.

What I am doing wrong?

Why the xml file remain being used by a process ?

Please see the attached example.

Thanks in advance

Luis

' This is the sub in the main form
 
Dim MyDoc As New XmlDocument()
Dim NewElement As XmlElement = Nothing
Dim NewAtribute As XmlAttribute = Nothing
 
MyDoc.LoadXml("<XmlData></XmlData>") ' I allway will create the file
 
NewElement = MyDoc.CreateElement("Headers")
 
NewAtribute = MyDoc.CreateAttribute("Value1")
NewAtribute.Value = "1"
NewElement.Attributes.Append(NewAtribute)
 
NewAtribute = MyDoc.CreateAttribute("Value2")
NewAtribute.Value = "2"
NewElement.Attributes.Append(NewAtribute)
 
MyDoc.DocumentElement.AppendChild(NewElement)
 
...
... More rows are inserted as needed
...
 
 
Dim UserPath As String = Path.GetFullPath(Path.Combine (Environment.GetFolderPath   (Environment.SpecialFolder.LocalApplicationData), "..\\MyCompany\Cache"))
 
Dim Writer As XmlTextWriter = New XmlTextWriter(UserPath & "\MyFile.xml", Nothing)
 
Writer.Formatting = Formatting.Indented
 
' This allways write OK, the first time, and the next times....
MyDoc.Save(Writer) 
 
MyDoc = Nothing
 
ChildForm.ShowDialog() ' Here I call the child form
 
 
********************************************************************
 
 
Following the child form:
 
 
Private Sub ChildForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
Dim ListNodes_Headers As XmlNodeList = Nothing
Dim Node As XmlNode = Nothing
 
Dim MyDoc As New XmlDocument()
 
Dim UserPath As String = Path.GetFullPath(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "..\\MyCompany\Cache"))
 
' The following, fails after the first time
MyDoc.Load(UserPath & "\MyFile.xml") ' Here I receive the error
 
ListNodes_Headers = MyDoc.SelectNodes("//Headers")
 
For Each Node In ListNodes_Headers
 
    Dim Value1 as string = Node.Attributes("Value1").Value
    Dim Value2 as string = Node.Attributes("Value2").Value
 
Next
 
MyDoc = Nothing
 
End Sub

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