fc8 runs too slow sometimes

[Paula J. Lindsay]

Hi,
I am running a fc8 machine and things were going just fine until about a 
week ago.  Then, my machine started slowing down, almost to a crawl.
This is happening intermittently, but sometimes it lasts for 2 days.  
This makes the scientists hindered and they are getting frustrated that I
can't figure it out.  Here is a brief show of some of the processes.  
Are these zombie processes?

vwong    31766     1  0 08:07 ?        00:00:00 /usr/bin/dbus-launch 
--exit-with-session /usr/bin/startkde
vwong    31767     1  0 08:07 ?        00:00:00 /bin/dbus-daemon --fork 
--print-pid 4 --print-address 6 --session
vwong    31788     1  0 08:07 ?        00:00:00 
/usr/bin/gnome-keyring-daemon
vwong    31791     1  0 08:07 ?        00:00:00 /usr/bin/gpg-agent -s 
--daemon
vwong    31795     1  0 08:07 ?        00:00:12 /usr/bin/pulseaudio -D

The machine was just rebooted two days ago.  If these are zombie 
processes, I can reboot again, but does this mean I have to
reboot every two days?  Is there a program that sucks up the cpu time?  
Sendmail is running on this machine when it doesn't
need to and he is using kde.  Please, can anyone out there help?
Many thanks in advance,
Paula
 --

Paula J. Lindsay
IT Analyst III
Research Computing
10550 North Torrey Pines Road
La Jolla, CA  92037
858.784.9378 (office)
858.784.9301 (fax)
paula at scripps.edu