A few days ago we received a complaint from one of our customers. They found that after deleting all documents from it, a SharePoint document library that serves as the base of a custom application shows negative item count on the All Site Content page. We checked where this value comes from and found it is the ItemCount property of the SPList object. An additional side effect of this strange behavior is that the indexing fails because it cannot cast the negative value to an unsigned integer ( UInt32 ). We could reproduce the behavior using the following code. It assumes that the address of your site is your site is http://moss/site and the name of the document library is CopyTest . The code creates a folder and subfolders, copies it using the CopyTo() method of SPFolder class, and finally deletes the folders. string siteUrl = "http://moss/site"; using (SPSite site = new SPSite(siteUrl)) { using (_web = site.OpenWeb()) { SPList list = _web.Lists["CopyTest"]; Console.WriteLine("Items.Count:{0}, ItemCount:{1}", list.Items.Count, list.ItemCount); Console.WriteLine("Creating 1.0 folder ... "); SPFolder rootFolder = _web.GetFolder("/CopyTest"); SPFolder version1Folder = rootFolder.SubFolders.Add("/CopyTest/1.0"); version1Folder.Update(); list.Update(); Console.WriteLine("OK"); Console.WriteLine("Items.Count:{0}, ItemCount:{1}", list.Items.Count, list.ItemCount); Console.WriteLine("Creating Test1 in...