Failure decoding embedded permission set object After .Net service pack install

[David Hodges]

After installing the service packs from Framework 1.0 and 1.1 on my
W2k web server I get the above error on all applications.
I am at my wits end and finding nothing on Google that helps.

Here is the complete error:

Security Exception
Description: The application attempted to perform an operation not
allowed by the security policy. To grant this application the required
permission please contact your system administrator or change the
application's trust level in the configuration file.

Exception Details: System.Security .SecurityExcept ion: Failure decoding
embedded permission set object.

Source Error:

An unhandled exception was generated during the execution of the
current web request. Information regarding the origin and location of
the exception can be identified using the exception stack trace below.

Stack Trace:
[SecurityExcepti on: Failure decoding embedded permission set object.]
System.RuntimeT ype.CreateInsta nceImpl(Boolean publicOnly) +0
System.Activato r.CreateInstanc e(Type type, Boolean nonPublic) +66
System.RuntimeT ype.CreateInsta nceImpl(Binding Flags bindingAttr,
Binder binder, Object[] args, CultureInfo culture, Object[]
activationAttri butes) +277
System.Activato r.CreateInstanc e(Type type, BindingFlags
bindingAttr, Binder binder, Object[] args, CultureInfo culture,
Object[] activationAttri butes) +109

System.Web.Conf iguration.HttpC apabilitiesEval uator.Evaluate( HttpRequest
request) +719

System.Web.Conf iguration.HttpC apabilitiesBase .GetConfigCapab ilities(String
configKey, HttpRequest request) +43
System.Web.Http Request.get_Bro wser() +22
System.Web.UI.W ebControls.Vali dationSummary.O nPreRender(Even tArgs
e) +96
System.Web.UI.C ontrol.PreRende rRecursiveInter nal() +62
System.Web.UI.C ontrol.PreRende rRecursiveInter nal() +125
System.Web.UI.C ontrol.PreRende rRecursiveInter nal() +125
System.Web.UI.C ontrol.PreRende rRecursiveInter nal() +125
System.Web.UI.C ontrol.PreRende rRecursiveInter nal() +125
System.Web.UI.P age.ProcessRequ estMain() +2095
System.Web.UI.P age.ProcessRequ est() +118
System.Web.UI.P age.ProcessRequ est(HttpContext context) +18
System.Web.Call HandlerExecutio nStep.Execute() +179
System.Web.Http Application.Exe cuteStep(IExecu tionStep step,
Boolean& completedSynchr onously) +87
Any ideas?
Thanks,
David