inetinfo.exe takes 100% of cpu

We have clustered Dual PIII Xeon 500Mhz servers with 512Mb RAM, running NT4 SP6a & IIS4.
From time to time inetinfo.exe will take 50% of CPU resource (effectively hogging one of the dual cpu’s completely). At this point, the websites hang.
We can take the W3SVC offline, but cannot stop IIS Admin service, it thinks W3SVC is still running. Cannot kill inetinfo in taskmanager either. The only way for us to recover is to fail-over and reboot the server.
Anyone else had this problem, and did u find what was causing the problem?