IISAdmin service crash

We are on Windows 2003 server with IIS 6.0 and use ISAPI filter iis_sso.dll. We are running the IIS 6.0 in isolation mode 5.0.

At random times we get the following error message:

Connection_Abandoned_By_Inetinfo_Crash

At this point the IISAdmin service is terminated.

By restarting the IISAdmin service everything works fine again untill the next crash.

Does anybody has any idea how to solve this problem?