System.UnauthorizedAccessException with SPWebpartmanager - sharepoint

Question

We are running SharePoint 2010 farm. I have removed all access to a sitecollection "Provider" from a user group. "Provider" is the default sitecollection that a user logs in to.
We have a custom access denied page that inherits from "UnsecuredLayoutsPageBase" and has a masterpage that has spwebpartmanager.
<WebPartPages:SPWebPartManager ID="m" runat="Server" />
Now when a user from the group that does not have access to "Provider" logs in, sharepoint redirects to AccessDeniedPage. But SPWebPartManager (checked with .net reflector) throws System.UnauthorizedAccessException: Attempted to perform an unauthorized operation, as the user logged in doesn't have permissions.
Is there any way to run spwebpartmanager with elevated permissions? I couldn't find anything but the SPSecurity.RunWithElevatedPrivileges block, but that works with user code. How can i make OTB code run with elevated permissions? Any help is much appreciated. Thanks.
here is the stack trace.
System.UnauthorizedAccessException: Attempted to perform an unauthorized operation.
at Microsoft.SharePoint.Utilities.SPUtility.HandleAccessDenied(HttpContext context)
at Microsoft.SharePoint.Utilities.SPUtility.HandleAccessDenied(Exception ex)
at Microsoft.SharePoint.Library.SPRequest.OpenWeb(String bstrUrl, String& pbstrServerRelativeUrl, String& pbstrTitle, String& pbstrDescription, String& pbstrTitleResourceId, String& pbstrDescriptionResourceId, Guid& pguidID, String& pbstrRequestAccessEmail, UInt32& pwebVersion, Guid& pguidScopeId, UInt32& pnAuthorID, UInt32& pnLanguage, UInt32& pnLocale, UInt16& pnTimeZone, Boolean& bTime24, Int16& pnCollation, UInt32& pnCollationLCID, Int16& pnCalendarType, Int16& pnAdjustHijriDays, Int16& pnAltCalendarType, Boolean& pbShowWeeks, Int16& pnFirstWeekOfYear, UInt32& pnFirstDayOfWeek, Int16& pnWorkDays, Int16& pnWorkDayStartHour, Int16& pnWorkDayEndHour, Int16& pnMeetingCount, Int32& plFlags, Boolean& bConnectedToPortal, String& pbstrPortalUrl, String& pbstrPortalName, Int32& plWebTemplateId, Int16& pnProvisionConfig, String& pbstrDefaultTheme, String& pbstrDefaultThemeCSSUrl, String& pbstrThemedCssFolderUrl, String& pbstrAlternateCSSUrl, String& pbstrCustomizedCssFileList, String& pbstrCustomJSUrl, String& pbstrAlternateHeaderUrl, String& pbstrMasterUrl, String& pbstrCustomMasterUrl, String& pbstrSiteLogoUrl, String& pbstrSiteLogoDescription, Object& pvarUser, Boolean& pvarIsAuditor, UInt64& ppermMask, Boolean& bUserIsSiteAdmin, Boolean& bHasUniquePerm, Guid& pguidUserInfoListID, Guid& pguidUniqueNavParent, Int32& plSiteFlags, DateTime& pdtLastContentChange, DateTime& pdtLastSecurityChange, String& pbstrWelcomePage, Boolean& pbOverwriteMUICultures, Boolean& pbMUIEnabled, String& pbstrAlternateMUICultures, Int32& puiVersion, Int16& pnClientTag)
at Microsoft.SharePoint.SPWeb.InitWeb()
at Microsoft.SharePoint.SPWeb.get_WebTemplate()
at Microsoft.SharePoint.SPWeb.get_WebTemplateConfiguration()
at Microsoft.SharePoint.WebControls.ScriptLink.InitJs_Register(Page page)
at Microsoft.SharePoint.WebControls.ScriptLink.RegisterForControl(Control ctrl, Page page, String name, Boolean localizable, Boolean defer, Boolean loadAfterUI, String language)
at Microsoft.SharePoint.WebControls.ScriptLink.Register(Page page, String name, Boolean localizable, Boolean defer, Boolean loadAfterUI, String language, String uiVersion)
at Microsoft.SharePoint.WebControls.ScriptLink.RegisterOnDemand(Page page, String strKey, String strFile, Boolean localizable)
at Microsoft.SharePoint.WebControls.ScriptLink.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Answer 1

I would suggest creating a different master page without the web part manager in it.

Answer 2

We ran into a similar problem with a forms-based sign in page that runs when the user is not logged in.
To solve the issue, we had to switch the #Page directive from:
DynamicMasterPageFile="~masterurl/default.master"
to
MasterPageFile="~/_layouts/simple.master"
It was quite a challenge to determine the cause; had to override PrcessRequest() with a try/catch block and then look at the InnerException to get a clue what was causing the problem because in /_login/OurLoginPage.aspx it was hidden under a 403 error and only deep inside the stack trace we found the issue you talk about above.