powerbook problem
 

my powerbook developed a disturbing problem yesterday. it functions
normally except that starting up a new program takes an inordinate
amount of time (like minutes, where it used to take seconds). this
applies to all programs, even simple ones like TextEdit. starting up
the system takes minutes longer as well. while a program is loading
the system essentially freezes, responding to commands very slowly.
programs once a program is loaded everything goes back to normal speed
as far as I can tell. the problem came on suddenly. while I was
using the computer I opened Safari and it took minutes to load. I did
a reboot and it's been in slow-load-mode ever since.

I have 512 mb RAM (2 x 256) and a 1.25 ghz processor. I haven't
installed anything new recently. my 80 gig hd is almost full, but
it's been like that for probably a couple months.

help?