Getting Error in NW7.3 - An error occured during authscheme computation

Hi,

After installing the NW 7.3 SP02 we tried to open the portal URL getting this error in logon page, please help us to reslove this issue.

#2.0 #2011 10 12 20:08:07:089#+0530#Error#com.sap.portal.portal#
#EP-PIN-PRT#tc~epbc~prtc~core#C000AC10088101B800000000000026DC#14430150000000004#sap.com/irj#com.sap.portal.portal#Guest#0##CC466CC0F4DF11E09D0A000000DC2FC6#cc466cc0f4df11e09d0a000000dc2fc6#cc466cc0f4df11e09d0a000000dc2fc6#0#Thread[HTTP Worker [@1797195169],5,Dedicated_Application_Thread]#Plain##
An error occured during authscheme computation.
[EXCEPTION]
com.sap.portal.prt.broker.PortalModuleNotFoundException: Could not retrieve portal application com.sap.portal.runtime.logon
	at com.sap.portal.prt.broker.PortalAppBroker.ensurePortalModuleIsStarted(PortalAppBroker.java:640)
	at com.sap.portal.prt.broker.PortalAppBroker.getPortalModule(PortalAppBroker.java:320)
	at com.sap.portal.prt.component.PortalComponentContextFactory.createPortalComponentContext(PortalComponentContextFactory.java:140)
	at com.sap.portal.prt.component.PortalComponentContextFactory.getPortalComponentContext(PortalComponentContextFactory.java:82)
	at com.sap.portal.prt.component.PortalComponentContextFactory.getPortalComponentContext(PortalComponentContextFactory.java:55)
	at com.sap.portal.prt.component.PortalComponentRequest.getComponentContext(PortalComponentRequest.java:400) 

Regards

Prakash T