The cause of this exception when i was logged in as admin I've clicked the layout display mode then when i login into this user again the exception appears and any other user i'm logging with when click layout mode again the exception appears and lock this user forever and this is the full details of the Exeption :

PortalID: 0
PortalName: Orascom Training & Technology
UserID: 26
UserName: mo2men
ActiveTabID: 40
ActiveTabName: Home
RawURL: /Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: http://ott.star-ware.com/Default.aspx
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 5a9960bd-f267-41b5-a480-c29b3622e9c4
InnerException: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Web.UI.ControlCollection.AddAt
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>). ---> System.Web.HttpException: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>). at System.Web.UI.ControlCollection.AddAt(Int32 index, Control child) at DotNetNuke.UI.Skins.Pane.ProcessPane() at DotNetNuke.UI.Skins.Skin.ProcessPanes() at DotNetNuke.UI.Skins.Skin.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.AddedControl(Control control, Int32 index) at System.Web.UI.ControlCollection.Add(Control child) at DotNetNuke.Framework.DefaultPage.Page_Init(Object sender, EventArgs e) at System.Web.UI.Control.OnInit(EventArgs e) at System.Web.UI.Page.OnInit(EventArgs e) at DotNetNuke.Framework.PageBase.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
Source:

Here's the Version I'm using 05.04.04 (2)

this only happen if i changes the view mode to layout