'Provide value on 'System.Windows.Baml2006.TypeConverterMarkupExtension' threw an exception.'

The exception in the title is thrown when I open a window in WPF, the strange thing is that this does not happen on my Windows 7 development machine nor does it happen when it is deployed on Windows 7.

I only get this error on Windows XP, and only the second time that I open the window.

Here is the code to open the window:

ReportParametersWindow win = null;

      bool canOverWrite = _shownReports.Contains(rpt.FriendlyName);

      if (!(canOverWrite))
        win = new ReportParametersWindow(rpt.FriendlyName, rpt.ReportParameters, canOverWrite);
      else
        win = new ReportParametersWindow(rpt.FriendlyName, (container.ParametersWindow as ReportParametersWindow).Controls, canOverWrite);

      win.ShowDialog();

And the XAML for the window:

<Window xmlns:my="clr-namespace:MHA.Modules.Core.Controls;assembly=MHA.Modules.Core"  
    x:Class="MHA.Modules.Reports.Views.ReportParametersWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Parameters" Height="500" Width="600" MinWidth="500" MaxHeight="500" 
    Icon="/MHA.Modules.Reports;component/Images/Parameters.ico" SizeToContent="WidthAndHeight" 
    WindowStartupLocation="CenterScreen"
    xmlns:odc="clr-namespace:Odyssey.Controls;assembly=Odyssey" Closed="Window_Closed">

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
        <RowDefinition Height="40"/>
    </Grid.RowDefinitions>
    <ScrollViewer Grid.Row="0" Name="ScrollViewer1" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" CanContentScroll="True">
        <StackPanel Name="ParameterStack">
            <my:LocationCtl Text="Parameters for report - " Name="loc"/>
        </StackPanel>
    </ScrollViewer>
    <Grid Grid.Row="1">
        <Grid.ColumnDefinitions>
            &l