How to set the Default value for DropDown when post back

Question

I am working with MVC3. I have a dropdown that I need to set the default value from the database.

When I select a value in the dropdownlist I get a postback and the value I selected is selected even after the postback. How do I get the default value, <--Select Project--> as selected value again after the postback?

Models

namespace BugTracker.Models
{
    public class BugModel
    {
        public List<BugModel> InsertBug {get; set;}
        public List<BugModel> Bugs { get; set; }
        public Int16 BugID { get; set; }
        [Required(ErrorMessage = "Title is required")]
        public string Title { get; set; }
        [Required(ErrorMessage = "Description is required")]
        public string Description {get; set;}
        [Required(ErrorMessage = "Version is required")]
        public string Version { get; set; }
        [Required(ErrorMessage = "BuildNumber is required")]
        public string BuildNumber { get; set; }
        [Required(ErrorMessage = "CreatedDate is required")]
        public string CreatedDate { get; set; }
        [Required(ErrorMessage = "GetDate is required")]
        public string GetDate { get; set; }

        public List<BugModel> GetProjects { get; set; }
        public int ProjectID { get; set; }
        [Required(ErrorMessage = "ProjectName is required")]
        public string ProjectName { get; set; }

        public List<BugModel> GetEmployee {get; set;}
        public int EmployeeID { get; set; }
        public int CreatedByID { get; set; }
        [Required(ErrorMessage = "EmployeeName is required")]
        public string EmployeeName {get;set;}
        [Required(ErrorMessage = "CreatedBy is required")]
        public string CreatedBy { get; set; }

        public List<BugModel> GetCategory { get; set;}
        public int CategoryID { get; set; }
        [Required(ErrorMessage = "Category is required")]
        public string Category { get; set;}

        public List<BugModel> GetSeverity { get; set;}
        public int SeverityID { get; set; }
        [Required(ErrorMessage = "Severity is required")]
        public string Severity { get; set; }

        public List<BugModel> GetPriority { get; set; }
        public int PriorityID { get; set; }
        [Required(ErrorMessage = "Prirority is required")]
        public string Prirority { get; set;}

        public List<BugModel> GetReleasePhase { get; set;}
        public int ReleasePhaseID { get; set; }
        [Required(ErrorMessage = "ReleasePhase is required")]
        public string ReleasePhase { get; set;}

        public List<BugModel> GetTypes { get; set; }
        public int TypeID { get; set; }
        [Required(ErrorMessage = "Type is required")]
        public string Type { get; set; }
        public List<BugModel> GetBugHistory { get; set; }    
        [Required(ErrorMessage = "AssignTo is required")]
        public string AssignTo { get; set; }

    }
}

Controllers

[AcceptVerbs(HttpVerbs.Post)]    
public ActionResult BugDetails(FormCollection form,string Projects,string Prirority,string CreatedBy,BugModel model)    
{
var modelList = new List();    
ViewBag.Projects = new SelectList(GetProjects(), "ProjectId", "ProjectName");    
ViewBag.Prirority = new SelectList(GetPriority(), "PriorityID", "Prirority");    
ViewBag.CreatedBy = new SelectList(GetEmployee(), "EmployeeID", "EmployeeName");    
using (SqlConnection conn = new SqlConnection(@"Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=BugtrackerNew;Data Source=SSDEV5-HP\SQLEXPRESS"))    
{    
    SqlCommand dCmd = new SqlCommand("Filter", conn);    
    dCmd.CommandType = CommandType.StoredProcedure;    
    conn.Open();    
    dCmd.Parameters.Add(new SqlParameter("@ProjectID", Projects));    
    dCmd.Parameters.Add(new SqlParameter("@PriorityID",Prirority));    
    dCmd.Parameters.Add(new SqlParameter("@CreatedByID",CreatedBy));    
    SqlDataAdapter da = new SqlDataAdapter(dCmd);    
    DataSet ds = new DataSet();    
    da.Fill(ds);
    for (int i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)    
    {
        model.BugID = Convert.ToInt16(ds.Tables[0].Rows[i]["BugID"]);    
        model.Title = ds.Tables[0].Rows[i]["Title"].ToString();    
        model.Description = ds.Tables[0].Rows[i]["Description"].ToString();            
        conn.Close();             
        return View(modelList);
    }
}

View

using (Html.BeginForm())    
{ %>   
<%: Html.DropDownList("Projects", (SelectList)ViewBag.Projects)%>    
<%: Html.DropDownList("Prirority", (SelectList)ViewBag.Prirority, "Select Project")%>  
<%: Html.DropDownList("CreatedBy", (SelectList)ViewBag.CreatedBy, "--Select Project--")%>

Now I want to get default value when the page is posted back. But in MVC we have no page load method, so how do I do this?