IIS4 keeps shutting down.

About a week ago, IIS4 seems to keep shutting itself down. Web Publishing Services, FTP Publishing Services, and iisadmin. Initially I thought a hacker, but it ocurrs randomly and consistantly for about a week now. I setup a monitor that checks it every 2 minutes, and if it goes down, it automatically issues a restart. This has dampened my problem, but it shouldn’t stay like that. I can’t seem to find anything on the Internet that explains it exactly. Some are similar, but I get no error messages, nothing in the event log. I only have 64MB RAM on a P120, but it has been running like this for several years. Anyone have any ideas? Know of any good free sniffers that can tell me what traffic is causing this problem?