Seemingly more hangs

[#1]

It may just be perception, but I seem to be getting more instances of progs hanging, so that I have to use Ctrl Alt Del or even use the computers main switch and then reboot.
Computer is on XP Home
Amd Athlon 2400+ processor 80GB hard drive
512 (2*256)MB PC 2700 DDR RAM
I have very recently done a disk clean up and a defrag.
Suggestions as to probable cause and cures would be much appreciated.
Thanks

[#2]

OOps finger slipped and wrong board. Reposted  elsewhere.

[#3]

Lockinated then.