WinForms and Threading Question/Problem

I have a windows application that grabs an XML file, parses the XML and grabs the fields, and then writes the data to a text file. (It will go into a database once i figure the problem out.) I can parse the XML file, i can write it to a file, my problem is that it takes about 1 minute to parse the XML file, its huge, i cant do anythign else on the form, i cant even minimize the form until the parsing completes. This is a problem, i need to be able to do other things while this thing is parsing. So i added threads, and that works, i have it parsing in its own thread, but same problem occures. I cant do anthing else to the app once the parser starts. I must wait till it completes, how can i get around this? I thought threads would be my answer, and maybe it still is, i am just missing something. Thanks for the help.

How does your thread work? off the top of my head, this is how I'd do it...

PHP Code:

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using System.Threading;

void BtnParse_Click(object sender, System.EventArgs e)
{
    
    Thread tXmlThread = new Thread(new ThreadStart(myXMLproc) );
    tXmlThread.Start();

}

void myXMLproc()
{
    // let the user know what's going on...
    myStatusBar.Text = "Processing XML File...."

    while(not_done_processing); // do your stuff

    myStatusBar.Text = "Done Processing XML File!"
    MessageBox.Show("XML Parsing complete!");
    
    return;
} 


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This code is in my main form.

PHP Code:

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private void btnParse_Click(object sender, System.EventArgs e)
{ 
     Parser p = new Parser();
     p.ParseXML();
} 


---

This code is my parser class.

PHP Code:

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public void ParseXML()
{
     Thread t1 = new Thread(new ThreadStart(ParseFile));
     t1.IsBackground = true;
     t1.Start();
} 


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The rest is what grabs the file and parses it. Nothing related to the threads is in that.