Programs and lib's disappearing, FreeBSD 5.4

[Nick Larsen]

Hi,

I love FreeBSD, but lately I've found in version 5.4-RELEASE every so
often I won't be able to run a program as it depends on a library
(which used to be there).

Eg: today i tried to access my webserver...Failed... So I SSH'd into
the box and ran
# apachectl start

It complained that it couldn't find libsasl2.so.2 which was needed by
modules/libphp4.so, but my web server had been working fine other
days, with absolutely no changes.
I fixed this problem, and then it couldnt find some *expat*.so.5 file,
which i then created sym links in /lib and /usr/lib (as it resides in
/usr/local/lib)

Later on today, I tried to sudo a command, and got...
bash: sudo: command not found

I had to reinstall sudo.

I'm extremely cofused, and have checked auth.log (My passwords are
quite difficult to crack as they have no meaning).