Current thread must be set to single thread apartment (STA) mode before OLE

I recently updated a simple program that uses a filedialog control to locate  
a file.  When I try and run the following code I get this error:  
Current thread must be set to single thread apartment (STA) mode before OLE  
calls can be made. Ensure that your Main function has STAThreadAttribute  
marked on it. This exception is only raised if a debugger is attached to the  
process.  
Here is the code  
this.openFileDialog1.FileName = this.txtCompilePath.Text;  
DialogResult result = openFileDialog1.ShowDialog(this);  
if (openFileDialog1.ShowDialog() == DialogResult.OK)  
{  
this.txtCompilePath.Text = openFileDialog1.FileName;  
}