Here is a fast note from the pain of experience. Aimed at new users:

/etc is where your gnu/linux stores it's configuration. Its function is similar to the Windoze registry. As you install, uninstall, and work with various programs, /etc changes. Sometimes, things change that make your system act unexpectedly.

A fairly easy way to backup, is to use a script. Don't panic, it's not difficult.

----- ----- -----

1) open a console
2) su
enter root password
3) # mkdir /var/backup
4) # vim /usr/sbin/prep4change
replace "vim" with text editor of your choice
5) cut and paste the following short script
##snip##
#!/bin/bash
Filename=/var/backup/$(date +%Y-%b-%d_%H:%M).bz2
echo "What is about to happen?"
read Note
echo $Filename."~".$Note >> /var/backup/notes
tar -cjf $Filename /etc/ /boot/
##snip##
6) save the file, and exit your editor
7) chmod 755 /usr/sbin/prep4change
this makes the script "executable"

----- ----- -----

All done!
Next time you are about to install, remove, or change something, just issue prep4change as root.

If the unthinkable ( but expected ) should happen, and things stop working correctly, you have your /etc and /boot already backed up.

Your backup will be located in /var/backup
You can also $ tail /var/backup/notes to see why you made what backup

Again, this isn't the most elegant, but it's simple, and it works! From my experience, the more bells and whistles something has, the more can go wrong!

Good you learned that, though hard way.