尝试读取或写入受保护的内存。这通常只是其他内存已损坏

这个是图片显示的页面，   有时能打开有时就报错
“/”应用程序中的服务器错误。
--------------------------------------------------------------------------------尝试读取或写入受保护的内存。这通常指示其他内存已损坏。 
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.AccessViolationException: 尝试读取或写入受保护的内存。这通常指示其他内存已损坏。源错误: 
行 88:             string[] src = img.Src.Split('\\');
行 89: 
行 90:             if (File.Exists(FileHelper.GetVirtualDirectory() + "\\" + img.Src))
行 91:             {
行 92:                 if (File.Exists(FileHelper.GetVirtualDirectory() + "\\" + src[0] + "\\" + src[1] + "\\x95_" + src[2]))
 源文件: e:\project\ProjectSln\backAdmin\bgPage\_uploadList.aspx.cs    行: 90 堆栈跟踪: 
[AccessViolationException: 尝试读取或写入受保护的内存。这通常指示其他内存已损坏。]
   System.DirectoryServices.Interop.UnsafeNativeMethods.IntADsOpenObject(String path, String userName, String password, Int32 flags, Guid& iid, Object& ppObject) +0
   System.DirectoryServices.Interop.UnsafeNativeMethods.ADsOpenObject(String path, String userName, String password, Int32 flags, Guid& iid, Object& ppObject) +30
   System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail) +325
   System.DirectoryServices.DirectoryEntry.Bind() +36
   System.DirectoryServices.DirectoryEntry.get_IsContainer() +31
   System.DirectoryServices.ChildEnumerator..ctor(DirectoryEntry container) +23
   System.DirectoryServices.DirectoryEntries.GetEnumerator() +25
   Rpw.Common.FileHelper.GetVirtualDirectory() +178
   backAdmin_bgPage_uploadList.dl_bindList_ItemDataBound(Object sender, DataListItemEventArgs e) in e:\project\ProjectSln\backAdmin\bgPage\_uploadList.aspx.cs:90
   System.Web.UI.WebControls.DataList.OnItemDataBound(DataListItemEventArgs e) +105
   System.Web.UI.WebControls.DataList.CreateItem(Int32 itemIndex, ListItemType itemType, Boolean dataBind, Object dataItem) +142
   System.Web.UI.WebControls.DataList.CreateControlHierarchy(Boolean useDataSource) +634
   System.Web.UI.WebControls.BaseDataList.OnDataBinding(EventArgs e) +56
   System.Web.UI.WebControls.BaseDataList.DataBind() +72
   backAdmin_bgPage_uploadList.bindlist() in e:\project\ProjectSln\backAdmin\bgPage\_uploadList.aspx.cs:71
   backAdmin_bgPage_uploadList.Page_Load(Object sender, EventArgs e) in e:\project\ProjectSln\backAdmin\bgPage\_uploadList.aspx.cs:23
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +15
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +34
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +47
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1061