Ernesto,
The problem returned and a reboot of the SharePoint servers resolved it. I suspect it may return again.
The forms are published via Central Administration as administrator approved form templates. Oddly, one out of five forms is not effected. The form not effected is submitting to DBXL, the three forms that case errors when rendering for the web are submitting to SharePoint directly.
Error
An unexpected error has occurred.
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Troubleshoot issues with Microsoft SharePoint Foundation.
Correlation ID: 2f7bb7a8-935b-4be2-89e2-da7743442529
=================
Business logic failed due to an exception. (User: XXXXX\XXXX, Form Name: DDE-Note_Form-MTN, IP: , Request: http://sharepoint/DDE/SiteAssets/EnterMTN.aspx, Form ID: urn:schemas-microsoft-com:office:infopath:DDE-Note-Form-MTN:-myXSD-2012-08-30T20-50-05, Type: SecurityException, Exception Message: Request for the permission of type 'System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.)
Product: InfoPath Forms Services Category: Runtime - Business Logic
Process: w3wp.exe (0x0FA0) Decimal: 4000
Thread (Hex): 0x0620 Decimal: 1568
EventID: 82g6 Level: Warning
Correlation: 2f7bb7a8-935b-4be2-89e2-da7743442529
=================
Exception thrown from business logic event listener: System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet)
at System.Security.PermissionSet.Demand()
at Microsoft.Office.InfoPath.Server.DocumentLifetime.OMSecurityContext.ExecuteOMCall(Solution solution, SecurityLevel methodSecurityLevel, ExceptionFilter exceptionFilter, OMCall d)
at Microsoft.Office.InfoPath.Server.DocumentLifetime.XmlFormHost.get_NamespaceManager()
at Microsoft.Office.InfoPath.Server.SolutionLifetime.XmlFormProxy.get_NamespaceManager()
at Qdabra.Tools.RulesLibrary.qRulesMain.get_NamespaceManager()
at Qdabra.Tools.RulesLibrary.qRulesMain.ExecuteCommand(XmlEventArgs e)
at Microsoft.Office.InfoPath.Server.SolutionLifetime.XmlEventExternal.<>c__DisplayClass10.<>c__DisplayClass14.<add_Changed>b__d()
at Microsoft.Office.InfoPath.Server.Util.DocumentReliability.InvokeBusinessLogic(Thunk thunk)
at Microsoft.Office.InfoPath.Server.SolutionLifetime.XmlEventExternal.<>c__DisplayClass20.<FireChangedEvent>b__1c()
at Microsoft.Office.InfoPath.Server.DocumentLifetime.OMExceptionManager.CallFormCodeWithExceptionHandling(UserMessages userMessages, OMCall d) The action that failed was: Demand The type of the first permission that failed was: System.Security.Permissions.UrlIdentityPermission The first permission that failed was: <IPermission class="System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Url="file:///C:/Windows/assembly/GAC_MSIL/Microsoft.Office.InfoPath.Server/14.0.0.0__71e9bce111e9429c"/> The demand was for: <PermissionSet class="System.Security.PermissionSet" version="1"> <IPermission class="System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Url="file:///C:/Windows/assembly/GAC_MSIL/Microsoft.Office.InfoPath.Server/14.0.0.0__71e9bce111e9429c"/> <IPermission class="System.Security.Permissions.ZoneIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Zone="MyComputer"/> </PermissionSet> The granted set of the failing assembly was: <PermissionSet class="System.Security.PermissionSet" version="1"> <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="Execution"/> <IPermission class="System.Security.Permissions.StrongNameIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" PublicKeyBlob="0024000004800000940000000602000000240000525341310004000001000100AD35B3D910CF66CE6E16316D8B7874EDC6737661AC3CF7220594AD38ABA0F5E6143E11A56EE14546DEBB8C8B52CF16DA8D83517F418CFE4F0D3D51DCF5D19817F9B64FFA50DACA6C94780FE12F24B35DB496B7807604533F6FD8CA6B9940D0BB2548B9D26F9A75191026572705DD0D3E7ABEF7AA5A10AFFB0CA1D304FC5A47C6" Name="Qdabra.Tools.RulesLibrary" AssemblyVersion="4.2.4575.29315"/> <IPermission class="System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Url="file:///C:/inetpub/wwwroot/wss/VirtualDirectories/SharePoint80/"/> <IPermission class="System.Security.Permissions.ZoneIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Zone="MyComputer"/> <IPermission class="System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Level="Minimal"/> <IPermission class="Microsoft.SharePoint.Security.WebPartPermission, Microsoft.SharePoint.Security, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" version="1" Connections="True"/> </PermissionSet> The assembly or AppDomain that failed was: Qdabra.Tools.RulesLibrary, Version=4.2.4575.29315, Culture=neutral, PublicKeyToken=0582df40855a0fba The method that caused the failure was: System.Xml.XmlNamespaceManager get_NamespaceManager() The Zone of the assembly that failed was: MyComputer The Url of the assembly that failed was: file:///C:/inetpub/wwwroot/wss/VirtualDirectories/SharePoint80/
Product: InfoPath Forms Services Category: Runtime - Business Logic
Process: w3wp.exe (0x0FA0) Decimal: 4000
Thread (Hex): 0x0620 Decimal: 1568
EventID: 7tg3 Level: Medium
Correlation: 2f7bb7a8-935b-4be2-89e2-da7743442529
=================
Request for the permission of type 'System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
Product: InfoPath Forms Services Category: Runtime
Process: w3wp.exe (0x0FA0) Decimal: 4000
Thread (Hex): 0x0620 Decimal: 1568
EventID: 6615 Level: Critical
Correlation: 2f7bb7a8-935b-4be2-89e2-da7743442529