I was running FC3 with kernel 2.6.10-1.766 and kernel-utils 2.4-13.1.39.
Yesterday, I upgraded the kernel to 2.6.11-1.14 and then 2.6.11-1.20.
Meanwhile, I also upgraded kernel-utils from 2.4-13.1.39 to 2.4-13.1.49.
Then I had difficulties to run FC3 smoothly. Everything has been slowed
down significantly. And I could find core.xxxx sometimes after booting
the system. I used rpm -iUh to upgrade kernel-utils.

I tried to uninstall the latest kernel (went back to original 2.6.10-1.766)
but did not help at all. So I guess maybe kernel-utils is the reason to
slow down the system. So how can I test the 39 version instead of the
current 49? Cannot remove it by simply using rpm -e or
rpm -nodeps -ivh kernel-utils.2.4-13.1.39.

What should I do now to fix the problem?
I am sure it is not caused by virus coz I unchecked all ports while
configuring firewall which means I do not trust any port. Maybe too
strict but I just want to be safe.

thanks very much for your help!