svchost.exe with rasman.dll uses up cpu

I have this problem on a desktop and a Dell laptop. Laptop is a clean
install. It runs fine for a while and then the svchost.exe server runs wild
and eats all the cpu resources. The laptop slows to a crawl. I used Process
Explorer and stopped each process individually. Nothing changed until I tried
to stop RASMAN.DLL. It will not stop. Using SERVICES to stop I get the
following error. "An access denied error was returned while attempting to
change a service. You may need to log on using an Administrator account to
make the specified change." I only have the Admin account on the laptop. This
error occurs on all three of my systems running XP (home and prof) when I try
to stop RASMAN.DLL. If I used msconfig and turn off RASMAN.DLL in the
services tab, the system seems to run fine. It is hard to be sure with a
problem this erratic. Can anyone shed any light on this?