So Gutsy users also have this problem? If anyone wants to contribute to a fix, then please subscribe to this bug (So that you get notified when someone posts a new comment). Great, we know what the problem is - now we need to start finding out what makes Dapper different from the newer versions. I've found the following instructions from DicOOo-1.8 (The dictionary installation thingy) which should give us some clues...

/*
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*** Instructions from DicOOo-1.8 on Dapper, which mentions a number of OO's configuration directories ***
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Debian GNU/Linux: (thanks Claude)
If you are using an OOo packaged by Debian (.deb), please note that in order to use the wizard, you first need to delete the symbolic link @dictionary.lst in the directory-folder:
	/usr/lib/openoffice/share/dict/ooo
and copy in its place the existing dictionary.lst file located in:
	/etc/openoffice
To do this you need to be logged in as root.
You also need to grant all users write permissions on the dictionary.lst file, if you want them to be able to install the dictionaries:
	chmod go+w dictionary.lst
Alternatively, if your users belong to the group users:
	chown root.users dictionary.lst
You can also start the wizard as root, if you do not want your users to be able to add dictionaries themselves.
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*/

/*
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*** This is my "/etc/openoffice/dictionary.lst" file (Probably won't be useful to anyone, but I posted here anyway) ***
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## !!! BEGIN AUTOMATIC SECTION -- DO NOT CHANGE !!!
## !!! ADD YOUR ADDITIONAL ENTRIES BELOW THIS SECTION !!!
DICT en GB en_GB
DICT en US en_US
THES en US th_en_US_v2
THES en GB th_en_US_v2
## !!! END AUTOMATIC SECTION -- DO NOT CHANGE !!!
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*/

... so, now we know where OO keeps its configuration data. It says some stuff about permissions too (In the DicOOo-1.8 instructions), which may explain why some people can't add dictionaries. Now we know where to start editing (But please go easy, I'm not responsible for anyone who blows up their installation). 

I think that a good place to start would be to have an affected user tell us the permissions of their "/etc/openoffice/dictionary.lst" file. Go into the "/etc/openoffice" directory and type in "ls -l" and find the permissions of "dictionary.lst". Mine says the following: "-rw-r--r-- 1 root root  911 2007-08-28 12:24 dictionary.lst". Are yours different?

Come on people, team effort! =D This is a simple error which could be fixed by a ten yearold. I've pointed us in the right direction, now lets kick some ass!