why iwserver process always use cpu 99%

System

I use teamsite6.5 sp1 on windows 2000 server, before it runs well, but today after I use the workflow and upgrade my browser from firefox1.04 to ff1.05,
iwserver process is always use cpu resource up to 99%-100%, but I still can use teamsite function well, only speed is very very low.
I have check the log include iwserver.log and iwtrace.log and found nothing useful info.

did anyone meet this situation before? could you give me some suggestion?