In Windchill 10.1, Appletes are not opening, gives null pointer exceptions

Hi all,

In Windchill 10.1 M020, today suddenly all Applets which are accesible from utility's are not opens.

i tried Team Management, Life cycle Template Administrator, Policy Administrator are giving error, while opening Applets.

Please find the image of Error.

and the error stating this "

java.lang.NullPointerException

    at wt.fc.QueryStringDelegateFactory.getDelegate(QueryStringDelegateFactory.java:212)

    at wt.fc.ReferenceFactory.getReference(ReferenceFactory.java:254)

    at wt.clients.lifecycle.administrator.Util.getContext(Util.java:314)

    at wt.clients.lifecycle.administrator.LifeCycleAdminApplet.initialize(LifeCycleAdminApplet.java:719)

    at wt.clients.lifecycle.administrator.LifeCycleAdminApplet.initialize(LifeCycleAdminApplet.java:710)

    at wt.clients.lifecycle.administrator.LifeCycleAdminApplet.access$100(LifeCycleAdminApplet.java:106)

    at wt.clients.lifecycle.administrator.LifeCycleAdminApplet$WorkThread.run(LifeCycleAdminApplet.java:614)

"

Please advice.