ADAM Membership provider and SecurityIdentifier not serializable

[JB]

Hello,

I have a security problem using an Membership provider that accesses
ADAM. I got the code from
http://blogs.msdn.com/craigmcmurtry/archive/2005/03/04/385133.aspx and
some minor changes I got it to compile and work.

Most of it works fine, using the Web Site Administration Tool website
but when I try to edit a user (which I just created), I get the
following exception:

Type 'System.Security.Principal.SecurityIdentifier' in assembly
'mscorlib, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089' is not marked as serializable.

What's happening and how can I fix this?

TIA,
Jeroen