C#

A) It must contain at least one vowel. 
B) It cannot contain three consecutive vowels or three consecutive consonants. 
C) It cannot contain two consecutive occurrences of the same letter, except for 'ee' or 'oo'. 

<?xml version="1.0" encoding="utf-8"?>
<Contacts>
  <Contact>
    <ContactId>0</ContactId>
    <Prefix>
    </Prefix>
    <FirstName>Kevin</FirstName>
    <MiddleName>Marois</MiddleName>
    <LastName>Brian</LastName>
    <Suffix>
    </Suffix>
    <Birthday>1965-10-11</Birthday>
    <Title>Senior Software Engineer</Title>
    <Comments>has 25 years of development experience</Comments>
  </Contact>
  <Contact>
    <ContactId>1</ContactId>
    <Prefix>Dr.</Prefix>
    <FirstName>Henry</FirstName>
    <MiddleName>DeCarlo</MiddleName>
    <LastName>G</LastName>
    <Suffix>III</Suffix>
    <Birthday>1965-10-11</Birthday>
    <Title>Oral Surgeon</Title>
    <Comments>His office is over on 23rd street</Comments>
  </Contact>
  <Contact>
    <ContactId>2</ContactId>
    <Prefix>
    </Prefix>
    <FirstName>Mattew</FirstName>
    <MiddleName>Damon</MiddleName>
    <LastName>Paige </LastName>
    <Suffix>
    </Suffix>
    <Birthday>1970-10-08</Birthday>
    <Title>Actor</Title>
    <Comments>Excellent actor</Comments>
  </Contact>
</Contacts>

public void DeleteContact(int ContactId)
{
    XmlDocument doc = new XmlDocument();
    doc.Load(XMLFile);
    var path = "/contacts/contact[@ContactId='" + ContactId + "']";
    XmlNode t = doc.SelectSingleNode(path);
    t.ParentNode.RemoveChild(t);
    doc.Save(XMLFile);
}

void listBox_DrawItem(object sender, DrawItemEventArgs e)
{
    if (e.Index > -1)
    {
        if (e.Index == 0)
            e.Graphics.FillRectangle(Brushes.Red, e.Bounds);
        else if (e.Index == 1)
            e.Graphics.FillRectangle(Brushes.Green, e.Bounds);
        else
            e.DrawBackground();
        using (Brush textBrush = new SolidBrush(e.ForeColor))
        {
            e.Graphics.DrawString(lbxOutput.Items[e.Index].ToString(), e.Font, textBrush, e.Bounds.Location);
        }
    }
}