Tiger relaunches Finder whenever Finder icon is clicked in the Dock

Question

My wife's MacBook, a 13" late '06 running Tiger, began having a problem with Finder this evening. Whenever the Finder icon in the Dock is clicked, all Finder windows close, the desktop flashes black, and Finder relaunches.
If a folder alias is clicked from the Desktop, it opens without a problem-- it's only the Finder Dock icon. All other programs open normally.

Answer 1

When using the Finder's own Preference setting dialog box, what does it
show the "New Finder window opens" as being set to open? If it was
set at some point, and "Other" was used to choose something beyond
the default expectations, the Finder icon in Dock could launch or re-
launch something else with results unexpectedly quite different.
The usual default is something like "Home" (a user folder) or maybe the
"Computer" which may contain a window with the Hard Disk drive and
a Network orb; or the "Macintosh HD" (so - IF - the HDD icon is made to
be invisible to the Desktop, the Finder can be used to access it instead.)
So, for some reason or through some accident, glitch, or evidence of
some corruption elsewhere in the system, you have Finder in Dock
re-launching the Dock...(?)
If there is a different purpose chosen in the Finder's menu bar where
the preferences can be changed in a "General" control box, you can
see if you can re-assign the defaults as mentioned above, again.
If other user accounts don't act up, (and they should not, since it
is not a universal change if these are set different in one account)
when they are booted into, and the Finder icon in the Dock is clicked
and you can't get that to revert to the default option(s) that should be
in the Finder Preference selection; then the issue may be in Dock
preference files themselves. Those would be (probably) in the user
Library file and among .plist named items.
Since I am not sure of the location of those specific items without an
extensive folder-opening search in my OSX system to find which of
the few relevant locations this applicable .plist is actually to be found,
the two probable items to find and move to desktop, then restart, may
be the Dock preference .plist and the Finder preference .plist items.
A restart should bring those two items back as default-set replacement
.plists, so, if you were unable to simply re-set the Finder preference
panel to choose Home, Macintosh HD, or maybe Computer in there,
you may have to find these two .plist files, and move them from the
correct location, where the system should replace them on restart.
Routine and usual system maintenance and light repairs to disk and
disk permissions can be done by running Disk Utility from the booted
Installer disc's menu bar options; short of running the actual Install
mode, where the menu bar has a drop down menu (such as Finder
but says Installer) when the computer is running from the OSX install
disc's version of startup software, where this access is possible. To
do that, you put the disc#1 of the current OS X version installer in to
the optical drive and hold the C key down on startup. The first window
that will appear should be the choose language window, the second
one should be where you have a menu bar in Installer to find & launch
Disk Utility from. After running D.U.'s first aid on the Macintosh HD to
'repair disk', you can run the' repair disk utilities' and maybe click on
the name of the brand of hard disk drive (same location where name
Macintosh HD, different item) and then run Verify on the hard drive.
When done, quit Disk Utility, and choose Startup Manager item from
the Installer's drop down menu bar option list; and choose the Mac's
hard drive system and restart the computer. A lighter way to repair the
disk permissions you probably should've been using regularly, is in
the Utilities folder in the computer's system on hard disk drive. Simply
choose GO in the Finder's menu bar, select Utilities Folder, and then
when that folder opens on the desktop, find & double-click Disk Utility.
(In my system, I highlighted Disk Utility's name by clicking it once
so I could change it; in mine, the only change made was to add one
space in front of the name Disk Utility, and now it is the first item in
the Utilities folder, so it is easier to find & launch regularly. This re-
orders the alphabetical order of named items in that folder and puts
the one with a single space in front of the natural order. If you want
to bring another item up to appear out of order, you can add one or
more spaces, to re-order items in a folder to be first ahead of A,B,C.)
You probably didn't need to know any or all of this; but resetting the
Finder preference to see if you can get the Dock's Finder icon to
launch the original few defaults instead of itself; or remove the plists
for Dock and Finder, and restart to see if the proper settings occur.
Not sure, but if you remove the Dock .plist, if that would remove the
chosen symbiotic links (drag-to-dock app icons you moved there)
or if those would be in another location. Removing the Finder .plist
from the appropriate file in the system should be safe enough and
restart. And find out if someone had changed that Finder preference.
Performing routine and preventative maintenance can be easy; but it
may not correct some odd changed preference in an obscure location.
And won't fix some corruption caused by data being overwritten due to
a hard disk drive being too full for the system to function normally.
The problem will be resolved when you fix it...!
Good luck & happy computing!
{ started writing early + wrote too much = finished late. }