I upgraded my dnn website from version 04.08.00 to version 05.01.02. The installation process was ok. It only desplayed error installing Minimalextropy skin and others was success. When I visit my website, I cannot login. When I try to login(I enter username and password and click Login button) I get "An error occured" "Go back to website" message. I looked at the eventlog table and found this error in the logproperties column:

<LogProperties><LogProperty><PropertyName>AssemblyVersion</PropertyName><PropertyValue>5.1.2</PropertyValue></LogProperty><LogProperty><PropertyName>PortalID</PropertyName><PropertyValue>0</PropertyValue></LogProperty><LogProperty><PropertyName>PortalName</PropertyName><PropertyValue>Nutricia voor Professionals</PropertyValue></LogProperty><LogProperty><PropertyName>UserID</PropertyName><PropertyValue>-1</PropertyValue></LogProperty><LogProperty><PropertyName>UserName</PropertyName><PropertyValue /></LogProperty><LogProperty><PropertyName>ActiveTabID</PropertyName><PropertyValue>36</PropertyValue></LogProperty><LogProperty><PropertyName>ActiveTabName</PropertyName><PropertyValue>Login</PropertyValue></LogProperty><LogProperty><PropertyName>RawURL</PropertyName><PropertyValue>/Login/tabid/36/Default.aspx?returnurl=%2fDefault.aspx</PropertyValue></LogProperty><LogProperty><PropertyName>AbsoluteURL</PropertyName><PropertyValue>/Default.aspx</PropertyValue></LogProperty><LogProperty><PropertyName>AbsoluteURLReferrer</PropertyName><PropertyValue>http://localhost/Login/tabid/36/Default.aspx?returnurl=%2fDefault.aspx</PropertyValue></LogProperty><LogProperty><PropertyName>UserAgent</PropertyName><PropertyValue>Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.4) Gecko/20091016 Firefox/3.5.4 GTB5 (.NET CLR 3.5.30729)</PropertyValue></LogProperty><LogProperty><PropertyName>DefaultDataProvider</PropertyName><PropertyValue>DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider</PropertyValue></LogProperty><LogProperty><PropertyName>ExceptionGUID</PropertyName><PropertyValue>466b62ad-fcf7-4ba2-9209-9333e254ed82</PropertyValue></LogProperty><LogProperty><PropertyName>InnerException</PropertyName><PropertyValue>Failed to load view_state.  The control tree into which view_state is being loaded must match the control tree that was used to save view_state during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.</PropertyValue></LogProperty><LogProperty><PropertyName>FileName</PropertyName><PropertyValue /></LogProperty><LogProperty><PropertyName>FileLineNumber</PropertyName><PropertyValue>0</PropertyValue></LogProperty><LogProperty><PropertyName>FileColumnNumber</PropertyName><PropertyValue>0</PropertyValue></LogProperty><LogProperty><PropertyName>Method</PropertyName><PropertyValue>System.Web.UI.Control.Loadview_stateRecursive</PropertyValue></LogProperty><LogProperty><PropertyName>StackTrace</PropertyName><PropertyValue /></LogProperty><LogProperty><PropertyName>Message</PropertyName><PropertyValue>DotNetNuke.Services.Exceptions.PageLoadException: Failed to load view_state.  The control tree into which view_state is being loaded must match the control tree that was used to save view_state during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request. ---&gt; System.Web.HttpException: Failed to load view_state.  The control tree into which view_state is being loaded must match the control tree that was used to save view_state during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Control.LoadChildview_stateByIndex(ArrayList childState)     at System.Web.UI.Control.Loadview_stateRecursive(Object savedState)     at System.Web.UI.Page.LoadAllState()     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)     --- End of inner exception stack trace ---</PropertyValue></LogProperty><LogProperty><PropertyName>Source</PropertyName><PropertyValue /></LogProperty></LogProperties>

Can someone help me out of this.