ASPnet_wp.exe and CSRSS.exe

[Chitra]

We have our Web server hosted on Win 2K server. Whenever
there is some activity in the web page (clients running
queries etc), the CSRSS.exe takes 50-70% of the CPU time
and aspnet_wp.exe the rest. The performance is very slow.
If I restart the IIS(5.0) , then there is no problem for
a while (like a day).

I some times see 2 intances of the CSRSS.exe.
Any idea what is causing this CSRSS.exe to take up so
much processor time?
thanks