Portal Graphic Rendering problem

Recently we got an error on the mss giving suer slow respond
and in MSS - Overview - workoverview [attandance overview]
it shows this error 

This problem is normally got to do with the
IGS - internet graphic service


please do refer to the link it will teach you step by step to fix or pin point the error.
http://help.sap.com/saphelp_nwce10/helpdata/en/45/f15ed044c741b2e10000000a11466f/content.htm


in r3 use the transaction code "sigs" to check on it.
you can even see the process in rz20..

Well if all this while there wasnt any error and suddenly it gave out this error. The quickest way is to reboot th whole SAP system.