IWSS 3.1 build 1158 on Windows 2003 Standard with SP2.
In working hours the service uses over 90 % CPU, but in the evenings (when there are just a few home office users connected) it uses between 10 - 40 % of the CPU. This problem occurred suddenly, without any extra load to the server. This makes internet surfing slow. The server functions only as a proxy, not url-blocker.
Nothing interesting in the eventviewer, have tried restarting the server without any luck.