What does this error mean in asp.net 2.0 and C#

My site is built in ASP.NET 2.0 and C# using SQL 2005 Database. I am writing all the error to my db in table called Exceptions.

Lately I have noticed that on my Products page, this error keeps getting written to the Exception table a lot. And I am not able to replicate it, if I want to check it out.

 System.NullReferenceException: Object reference not set to an instance of an object. at MySite.products.showItems(Int32 pageIndex) in c:\Websites\gn4f4ada\browse\products.aspx.cs:line 547 at MySite.products.Page_Load(Object sender, EventArgs e) in c:\Websites\gn4f4ada\browse\products.aspx.cs:line 68

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in products.aspx.cs line 68 is

   try
            {
                if (!this.IsPostBack)
                {
                    this.CategoryId = Convert.ToInt32(Request[REQ_CATEGORY_ID]);
                    this.showItems(this.PageIndex);  // THIS IS LINE 68
                }
            }
            catch (Exception ex)
            {
                this.HandlePageError(ex);
            }

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and line 547

     private void showItems(int pageIndex)
        {
            Category view;
            if (SelectedSize > -1)
            {
                view = this.CurrentCategory.GetView(
                    (SizeType)SelectedSize,
                    (Gender)SelectedGender);
            }
            else
            {
                if (SelectedGender > 0)
                {
                    view = this.CurrentCategory.GetView((Gender)SelectedGender);
                }
                else
                {
                    view = this.CurrentCategory;
                }
            }

            this.pager.SetPagingLabels(view.ItemCount);  // THIS IS LINE 547

            if (this.ViewMode == MySitePage.ViewMode.Paged)
            {
                this.rProducts.DataSource = view.GetPage(pageIndex, this.pager.PageSize);
            }
            else
            {
                this.rProducts.DataSource = view.Items;
            }
            this.rProducts.DataBind();
        }

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any advice or suggestions are appreciated