I am using kernel-2.4.7-2.5 and usually leave myself
logged in over night. The last 2 days, I have turned on the monitor at 7
am and started typing along..  and found the machine to be very
un-responsive.. it seems the programs are all in swap and they all need
to be swapped back in.  Looking at the GNOME memory/swap/cpu counter,   
there is a flurry of activity as the memory bar moves to the top, and   
then seems to empty down to a minimal 32 megs or so (top reported the 
same thing). It then fills itself back up and many apps become useful 
again.

The funny thing is that certain apps like Mozilla, Xchat, Pan, and
Galeon do not get better.. you type on them, and it takes a while (up to
30 seconds) for the keyboard and screen to sink up with each other.
Looking at top, it reports that the process is out of swap.. but I dont
know how useful that is. I played around with x-chat this morning, and
it stayed in this ulta-nice'd state for about 10 minutes.. I finally
gave up and killed the apps and then start new ones. These new ones
function like normal.